Excitatory amino acid receptor antagonists

ABSTRACT

The present invention provides novel compounds of Formula I or Formula II, or the pharmaceutically acceptable salts or prodrugs thereof, pharmaceutical compositions comprising an effective amount of a compound of Formula I or Formula II in combination with a suitable carrier, diluent, or excipient, and methods for treating neurological disorders and neurodegenerative diseases, particularly pain and migraine.

BACKGROUND OF THE INVENTION

In the mammalian central nervous system (CNS), the transmission of nerveimpulses is controlled by the interaction between a neurotransmitter,that is released by a sending neuron, and a surface receptor on areceiving neuron, which causes excitation of this receiving neuron.L-Glutamate, which is the most abundant neurotransmitter in the CNS,mediates the major excitatory pathways in mammals, and is referred to asan excitatory amino acid (EAA). The receptors that respond to glutamateare called excitatory amino acid receptors (EAA receptors). See Watkins& Evans, Ann. Rev. Pharmacol. Toxicol., 21, 165 (1981); Monaghan,Bridges, and Cotman, Ann. Rev. Pharmacol. Toxicol., 29, 365 (1989);Watkins, Krogsgaard-Larsen, and Honore, Trans. Pharm. Sci., 11, 25(1990). The excitatory amino acids are of great physiologicalimportance, playing a role in a variety of physiological processes, suchas long-term potentiation (learning and memory), the development ofsynaptic plasticity, motor control, respiration, cardiovascularregulation, and sensory perception.

Excitatory amino acid receptors are classified into two general types.Receptors that are directly coupled to the opening of cation channels inthe cell membrane of the neurons are termed “ionotropic.” This type ofreceptor has been subdivided into at least three subtypes, which aredefined by the depolarizing actions of the selective agonistsN-methyl-D-aspartate (NMDA),α-mino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), and kainicacid (KA). Molecular biological studies have established that AMPAreceptors are composed of subunits (GluR₁-GluR₄), which can assemble toform functional ion channels. Five kainate receptors have beenidentified which are classified as either High Affinity (KA1 and KA2) orLow Affinity (composed of GluR₅, GluR₆, and/or GluR₇ subunits). Bleakmanet al., Molecular Pharmacology, 49, No. 4, 581, (1996). The secondgeneral type of receptor is the G-protein coupled or secondmessenger-linked “metabotropic” excitatory amino acid receptor. Thissecond type is coupled to multiple second messenger systems that lead toenhanced phosphoinositide hydrolysis, activation of phospholipase D,increases or decreases in cAMP formation, and changes in ion channelfunction. Schoepp and Conn, Trends in Pharmacol. Sci., 14, 13 (1993).Both types of excitatory amino acid receptor appear not only to mediatenormal synaptic transmission along excitatory pathways, but also toparticipate in the modification of synaptic connections duringdevelopment and throughout life. Schoepp, Bockaert, and Sladeczek,Trends in Pharmacol. Sci., 11, 508 (1990); McDonald and Johnson, BrainResearch Reviews, 15, 41 (1990).

The excessive or inappropriate stimulation of excitatory amino acidreceptors leads to neuronal cell damage or loss by way of a mechanismknown as excitotoxicity. This process has been suggested to mediateneuronal degeneration in a variety of neurological disorders andconditions. The medical consequences of such neuronal degeneration makesthe abatement of these degenerative neurological processes an importanttherapeutic goal. For instance, excitatory amino acid receptorexcitotoxicity has been implicated in the pathophysiology of numerousneurological disorders, including the etiology of cerebral deficitssubsequent to cardiac bypass surgery and grafting, stroke, cerebralischemia, spinal cord lesions resulting from trauma or inflammation,perinatal hypoxia, cardiac arrest, and hypoglycemic neuronal damage. Inaddition, excitotoxicity has been implicated in chronicneurodegenerative conditions including Alzheimer's Disease, Huntington'sChorea, inherited ataxias, AIDS-induced dementia, amyotrophic lateralsclerosis, idiopathic and drug-induced Parkinson's Disease, as well asocular damage and retinopathy. Other neurological disorders implicatedwith excitotoxicity and/or glutamate dysfunction include muscularspasticity including tremors, drug tolerance and withdrawal, brainedema, convulsive disorders including epilepsy, depression, anxiety andanxiety related disorders such as post-traumatic stress syndrome,tardive dyskinesia, and psychosis related to depression, schizophrenia,bipolar disorder, mania, and drug intoxication or addiction (seegenerally U.S. Pat. Nos. 5,446,051 and 5,670,516). Excitatory amino acidreceptor antagonists may also be useful as analgesic agents and fortreating or preventing various forms of headache, including clusterheadache, tension-type headache, and chronic daily headache. Inaddition, published International Patent application WO 98/45720 reportsthat excitatory amino acid receptor excitotoxicity participates in theetiology of acute and chronic pain states including severe pain,intractable pain, neuropathic pain, post-traumatic pain.

It is also known that trigeminal ganglia, and their associated nervepathways, are associated with painful sensations of the head and facesuch as headache and, in particular, migraine. Moskowitz (Cephalalgia,12, 5-7, (1992) proposed that unknown triggers stimulate the trigeminalganglia which in turn innervate vasculature within cephalic tissue,giving rise to the release of vasoactive neuropeptides from axonsinnervating the vasculature. These neuropeptides initiate a series ofevents leading to neurogenic inflammation of the meninges, a consequenceof which is pain. This neurogenic inflammation is blocked by sumatriptanat doses similar to those required to treat acute migraine in humans.However, such doses of sumatriptan are associated with contraindicationsas a result of sumatriptan's attendant vasoconstrictive properties. (seeMacIntyre, P. D., et al., British Journal of Clinical Pharmacology, 34,541-546 (1992); Chester, A. H., et al., Cardiovascular Research, 24,932-937 (1990); Conner, H. E., et al., European Journal of Pharmacology,161, 91-94 (1990)). Recently, it has been reported that all five membersof the kainate subtype of ionotropic glutamate receptors are expressedon rat trigeminal ganglion neurons, and in particular, high levels ofGluR₅ and KA2 have been observed. (Sahara et al., The Journal ofNeuroscience, 17(17), 6611 (1997)). As such, migraine presents yetanother neurological disorder which may be implicated with glutamatereceptor excitotoxicity.

The use of a neuroprotective agent, such as an excitatory amino acidreceptor antagonist, is believed to be useful in treating or preventingall of the aforementioned disorders and/or reducing the amount ofneurological damage associated with these disorders. For example,studies have shown that AMPA receptor antagonists are neuroprotective infocal and global ischemia models. The competitive AMPA receptorantagonist NBQX (2,3-dihydroxy-6-nitro-7-sulfamoylbenzo[f]quinoxaline)has been reported effective in preventing global and focal ischemicdamage. Sheardown et al., Science, 247, 571 (1900); Buchan et al.,Neuroreport, 2, 473 (1991); LePeillet et al., Brain Research, 571, 115(1992). The noncompetitive AMPA receptor antagonists GKYI 52466 has beenshown to be an effective neuroprotective agent in rat global ischemiamodels. LaPeillet et al., Brain Research, 571, 115 (1992). EuropeanPatent Application Publication No. 590789A1 and U.S. Pat. Nos. 5,446,051and 5,670,516 disclose that certain decahydroisoquinoline derivativecompounds are AMPA receptor antagonists and, as such, are useful in thetreatment of a multitude of disorders conditions, including pain andmigraine headache. WO 98/45270 discloses that certaindecahydroisoquinoline derivative compounds are selective antagonists ofthe iGluR₅ receptor and are useful for the treatment of various types ofpain, including; severe, chronic, intractable, and neuropathic pain.

In accordance with the present invention, Applicants have discoverednovel compounds that are antagonists of the iGluR₅ receptor subtype and,thus, could be useful in treating the multitude of neurologicaldisorders or neurodegenerative diseases, as discussed above. Suchantagonists could address a long felt need for safe and effectivetreatments for neruological disorders, without attending side effects.The treatment of neurological disorders and neurodegenerative diseasesis hereby furthered.

SUMMARY OF TH INVENTION

The present invention provides a compound of Formula I

Formula I

wherein,

-   -   R¹ represents hydrogen, chlorine, bromine, iodine, fluorine,        SR³, or hydroxy;    -   R² represents hydrogen or fluorine, with the proviso that where        R¹ is other than fluorine, then R² represents hydrogen; and    -   R³ represents tetrazole, substituted tetrazole, triazole,        (C₁-C₄)alkyl, or (C₁-C₄)alkyl-CO₂H;    -   with the further proviso that where R¹ and R² each independently        represent fluorine, the compound is of the formula    -   or a pharmaceutically acceptable salt or prodrug thereof.

In addition, the present invention provides a compound of Formula II

Formula II

wherein,

-   -   R⁹ represents hydrogen, chlorine, bromine, iodine, fluorine,        hydroxy, tetrazole, or a group of the formula:        wherein X represents (C₁-C₄)alkyl or phenyl; and    -   R¹⁰ represents hydrogen or fluorine, with the proviso that where        R⁹ is other than fluorine, then R¹⁰ represents hydrogen,    -   or a pharmaceutically acceptable salt or prodrug thereof.

In another embodiment, the present invention provides a method oftreating or preventing a neurological disorder, or neurodegenerativecondition, comprising administering to a patient in need thereof aneffective amount of a compound of Formula I or or Formula II, or apharmaceutically acceptable salt thereof. Examples of such neurologicaldisorders, or neurodegenerative conditions, include: cerebral deficitssubsequent to cardiac bypass surgery and grafting; stroke; cerebralischemia; spinal cord lesions resulting from trauma or inflammation;perinatal hypoxia; cardiac arrest; hypoglycemic neuronal damage;Alzheimer's Disease; Huntington's Chorea; inherited ataxias;AIDS-induced dementia; amyotrophic lateral sclerosis; idiopathic anddrug-induced Parkinson's Disease; ocular damage and retinopathy;muscular spasticity including tremors; drug tolerance and withdrawal;brain edema; convulsive disorders including epilepsy; depression;anxiety and anxiety related disorders such as post-traumatic stresssyndrome; tardive dyskinesia; psychosis related to depression,schizophrenia, bipolar disorder, mania, and drug intoxication oraddiction; headache, including cluster headache, tension-type headache,and chronic daily headache; migraine; and acute and chronic pain statesincluding severe pain, intractable pain, neuropathic pain, andpost-traumatic pain.

More specifically, the present invention provides a method of treatingor preventing pain or migraine comprising administering to a patient inneed thereof an effective amount of a compound of Formula I or FormulaII, or a pharmaceutically acceptable salt or prodrug thereof.

In addition, the present invention provides pharmaceutical compositionsof compounds of Formula I or Formula II, including the pharmaceuticallyacceptable salts, prodrugs, and hydrates thereof, comprising, a compoundof Formula I or Formula II in combination with a pharmaceuticallyacceptable carrier, diluent or excipient. This invention alsoencompasses novel intermediates, and processes for the synthesis of thecompounds of Formula I and Formula II.

The present invention also provides the use of a compound of Formula Ior Formula II for the manufacture of a medicament for treating orpreventing a neurological disorder, or neurodegenerative condition.

More specifically, the present invention provides the use of a compoundof Formula I or Formula II for the manufacture of a medicament fortreating or preventing pain or migraine.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides compounds functional as iGluR₅ receptorantagonists as well as pharmaceutically acceptable salts, prodrugs, andcompositions thereof. These compounds are useful in treating orpreventing neurological disorders, or neurodegenerative diseases,particularly pain and migraine. As such, methods for the treatment orprevention of neurological disorders, or neurodegenerative diseases, arealso provided by the present invention.

In addition, it should be understood by the skilled artisan that all ofthe compounds useful for the methods of the present invention areavailable for prodrug formulation. As used herein, the term “prodrug”refers to a compound of Formula I or Formula II which has beenstructurally modified such that in vivo the prodrug is converted, forexample, by hydrolytic, oxidative, reductive, or enzymatic cleavage intothe parent compound (e.g. the carboxylic acid (drug), or as the case maybe the parent dicarboxylic acid (drug)) as given by Formula I or FormulaII. Such prodrugs may be, for example, metabolically labile mono- ordi-ester derivatives of the parent compounds having a carboxylic acidgroup. It is to be understood that the present invention includes anysuch prodrugs, such as metabolically labile ester or diester derivativesof compounds of Formula I or Formula II. In all cases, the use of thecompounds described herein as prodrugs is contemplated, and often ispreferred, and thus, the prodrugs of all of the compounds provided areencompassed in the names of the compounds herein. Conventionalprocedures for the selection and preparation of suitable prodrugs arewell known to one of ordinary skill in the art.

More specifically, examples of prodrugs of Formula I which areunderstood to be included within the scope of the present invention, arerepresented by Formula Ia below:

wherein,

-   -   R² is as previously defined hereinabove;    -   R⁴ represents hydrogen, chlorine, bromine, iodine, fluorine,        SR⁷, or hydroxy, with the proviso that where R⁴ is other than        fluorine, then R² represents hydrogen;    -   R⁷ represents tetrazole, substituted tetrazole, triazole,        (C₁-C₄)alkyl, (C₁-C₄)alkyl-CO₂R⁸; and    -   R⁵, R⁶, and R⁸ each independently represent hydrogen,        (C₁-C₂₀)alkyl, (C₂-C₆)alkenyl, (C₁-C₆)alkylaryl,        (C₁-C₆)alkyl(C₃-C₁₀)cycloalkyl, (C₁-C₆)alkyl-N,N—C₁-C₆        dialkylamine, (C₁-C₆)alkyl-pyrrolidine, (C₁-C₆)alkyl-piperidine,        or (C₁-C₆)alkyl-morpholine, with the proviso that at least one        of R⁵, R⁶, or R⁸ is other than hydrogen;    -   with the further proviso that where R² and R⁴ each independently        represent fluorine, then the compound is of the formula    -   or a pharmaceutically acceptable salt thereof.

Examples of prodrugs of Formula II, which are also understood to beincluded within the scope of the present invention, are represented byFormula IIa below:

wherein,

-   -   R⁹ and R¹⁰ are as defined hereinabove; and    -   R¹¹ and R¹² each independently represent hydrogen,        (C₁-C₂₀)alkyl, (C₂-C₆)alkenyl, (C₁-C₆)alkylaryl,        (C₁-C₆)alkyl(C₃-C₁₀)cycloalkyl, (C₁-C₆)alkyl-N,N—C₁-C₆        dialkylamine, (C₁-C₆)alkyl-pyrrolidine, (C₁-C₆)alkyl-piperidine,        or (C₁-C₆)alkyl-morpholine, with the proviso that at least one        of R¹¹ or R¹² is other than hydrogen,    -   or a pharmaceutically acceptable salt thereof.

It is understood that the iGluR₅ receptor antagonists of the presentinvention may exist as pharmaceutically acceptable salts and, as such,salts are therefore included within the scope of the present invention.The term “pharmaceutically acceptable salt” as used herein, refers tosalts of the compounds provided by, or employed in the present inventionwhich are substantially non-toxic to living organisms. Typicalpharmaceutically acceptable salts include those salts prepared byreaction of the compounds of the present invention with apharmaceutically acceptable mineral or organic acid or an organic orinorganic base. Such salts are known as acid addition and base additionsalts.

It will be understood by the skilled reader that most or all of thecompounds used in the present invention are capable of forming salts,and that the salt forms of pharmaceuticals are commonly used, oftenbecause they are more readily crystallized and purified than are thefree bases. In all cases, the use of the pharmaceuticals describedherein as salts is contemplated in the description herein, and often ispreferred, and the pharmaceutically acceptable salts of all of thecompounds are included in the names of them.

Acids commonly employed to form acid addition salts are inorganic acidssuch as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuricacid, phosphoric acid, and the like, and organic acids such asp-toluenesulfonic, methanesulfonic acid, oxalic acid,p-bromophenylsulfonic acid, carbonic acid, succinic acid, citric acid,benzoic acid, acetic acid, and the like. Examples of suchpharmaceutically acceptable salts are the sulfate, pyrosulfate,bisulfate, sulfite, bisulfite, phosphate, monohydrogenphosphate,dihydrogenphosphate, metaphosphate, pyrophosphate, bromide, iodide,hydroiodide, dihydroiodide, acetate, propionate, decanoate, caprylate,acrylate, formate, hydrochloride, dihydrochloride, isobutyrate,caproate, heptanoate, propiolate, oxalate, malonate, succinate,suberate, sebacate, fumarate, maleate, butyne-1,4-dioate,hexyne-1,6-dioate, benzoate, chlorobenzoate, methylbenzoate,hydroxybenzoate, methoxybenzoate, phthalate, xylenesulfonate,phenylacetate, phenylpropionate, phenylbutyrate, citrate, lactate,α-hydroxybutyrate, glycolate, tartrate, methanesulfonate,propanesulfonate, naphthalene-1-sulfonate, napththalene-2-sulfonate,mandelate and the like. Preferred pharmaceutically acceptable acidaddition salts are those formed with mineral acids such as hydrochloricacid and hydrobromic acid, and those formed with organic acids such asmaleic acid, mandelic acid, and methanesulfonic acid.

Base addition salts include those derived from inorganic bases, such asammonium or alkali or alkaline earth metal hydroxides, carbonates,bicarbonates, and the like. Such bases useful in preparing the salts ofthis invention thus include sodium hydroxide, potassium hydroxide,ammonium hydroxide, potassium carbonate, sodium carbonate, sodiumbicarbonate, potassium bicarbonate, calcium hydroxide, calciumcarbonate, and the like. The potassium and sodium salt forms areparticularly preferred. It should be recognized that the particularcounterion forming a part of any salt of this invention is usually notof a critical nature, so long as the salt as a whole ispharmacologically acceptable and as long as the counterion does notcontribute undesired qualities to the salt as a whole. It is furtherunderstood that such salts may exist as a hydrate.

As used herein, the term “stereoisomer” refers to a compound made up ofthe same atoms bonded by the same bonds but having differentthree-dimensional structures which are not interchangeable. Thethree-dimensional structures are called configurations. As used herein,the term “enantiomer” refers to two stereoisomers whose molecules arenonsuperimposable mirror images of one another. The term “chiral center”refers to a carbon atom to which four different groups are attached. Asused herein, the term “diastereomers” refers to stereoisomers which arenot enantiomers. In addition, two diastereomers which have a differentconfiguration at only one chiral center are referred to herein as“epimers”. The terms “racemate”, “racemic mixture” or “racemicmodification” refer to a mixture of equal parts of enantiomers.

The term “enantiomeric enrichment” as used herein refers to the increasein the amount of one enantiomer as compared to the other. A convenientmethod of expressing the enantiomeric enrichment achieved is the conceptof enantiomeric excess, or “ee”, which is found using the followingequation: ${ee} = {\frac{E^{1} - E^{2}}{E^{1} + E^{2}} \times 100}$wherein E¹ is the amount of the first enantiomer and E² is the amount ofthe second enantiomer. Thus, if the initial ratio of the two enantiomersis 50:50, such as is present in a racemic mixture, and an enantiomericenrichment sufficient to produce a final ratio of 50:30 is achieved, theee with respect to the first enantiomer is 25%. However, if the finalratio is 90:10, the ee with respect to the first enantiomer is 80%. Anee of greater than 90% is preferred, an ee of greater than 95% is mostpreferred and an ee of greater than 99% is most especially preferred.Enantiomeric enrichment is readily determined by one of ordinary skillin the art using standard techniques and procedures, such as gas or highperformance liquid chromatography with a chiral column. Choice of theappropriate chiral column, eluent and conditions necessary to effectseparation of the enantiomeric pair is well within the knowledge of oneof ordinary skill in the art. In addition, the enantiomers of compoundsof Formula I and Fromula II can be resolved by one of ordinary skill inthe art using standard techniques well known in the art, such as thosedescribed by J. Jacques, et al., “Enantiomers, Racemates, andResolutions”, John Wiley and Sons, Inc., 1981.

The compounds of the present invention have one or more chiral centersand may exist in a variety of stereoisomeric configurations. As aconsequence of these chiral centers, the compounds of the presentinvention occur as racemates, mixtures of enantiomers and as individualenantiomers, as well as diastereomers and mixtures of diastereomers. Allsuch racemates, enantiomers, and diastereomers are within the scope ofthe present invention.

The terms “R” and “S” are used herein as commonly used in organicchemistry to denote specific configuration of a chiral center. The term“R” (rectus) refers to that configuration of a chiral center with aclockwise relationship of group priorities (highest to second lowest)when viewed along the bond toward the lowest priority group. The term“S” (sinister) refers to that configuration of a chiral center with acounterclockwise relationship of group priorities (highest to secondlowest) when viewed along the bond toward the lowest priority group. Thepriority of groups is based upon their atomic number (in order ofdecreasing atomic number). A partial list of priorities and a discussionof stereochemistry is contained in “Nomenclature of Organic Compounds:Principles and Practice”, (J. H. Fletcher, et al., eds., 1974) at pages103-120.

The specific stereoisomers and enantiomers of compounds of Formula I andFormula II can be prepared by one of ordinary skill in the art utilizingwell known techniques and processes, such as those disclosed by Elieland Wilen, “Stereochemistry of Organic Compounds”, John Wiley & Sons,Inc., 1994, Chapter 7, Separation of Stereoisomers. Resolution.Racemization, and by Collet and Wilen, “Enantiomers, Racemates, andResolutions”, John Wiley & Sons, Inc., 1981. For example, the specificstereoisomers and enantiomers can be prepared by stereospecificsyntheses using enantiomerically and geometrically pure, orenantiomerically or geometrically enriched starting materials. Inaddition, the specific stereoisomers and enantiomers can be resolved andrecovered by techniques such as chromatography on chiral stationaryphases, enzymatic resolution or fractional recrystallization of additionsalts formed by reagents used for that purpose.

As used herein the term “Pg” or “PG” refers to a suitable nitrogenprotecting group. Examples of a suitable nitrogen protecting group asused herein refers to those groups intended to protect or block thenitrogen group against undesirable reactions during syntheticprocedures. Choice of the suitable nitrogen protecting group used willdepend upon the conditions that will be employed in subsequent reactionsteps wherein protection is required, and is well within the knowledgeof one of ordinary skill in the art. Commonly used nitrogen protectinggroups are disclosed in Greene, “Protective Groups In OrganicSynthesis,” (John Wiley & Sons, New York (1981)). Suitable nitrogenprotecting groups comprise acyl groups such as formyl, acetyl,propionyl, pivaloyl, t-butylacetyl, 2-chloroacetyl, 2-bromoacetyl,trifluoroacetyl, trichloroacetyl, phthalyl, o-nitrophenoxyacetyl,.alpha.-chlorobutyryl, benzoyl, 4-chlorobenzoyl, 4-bromobenzoyl,4-nitrobenzoyl, and the like; sulfonyl groups such as benzenesulfonyl,p-toluenesulfonyl and the like; carbamate forming groups such asbenzyloxycarbonyl, p-chlorobenzyloxycarbonyl,p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl,2-nitrobenzyloxycarbonyl, p-bromobenzyloxycarbonyl,3,4-dimethoxybenzyloxycarbonyl, 3,5-dimethoxybenzyloxycarbonyl,2,4-dimethoxybenzyloxycarbonyl, 4-methoxybenzyloxycarbonyl,2-nitro-4,5-dimethoxybenzyloxycarbonyl,3,4,5-trimethoxybenzyloxycarbonyl,1-(p-biphenylyl)-1-methylethoxycarbonyl,.alpha.,.alpha.-dimethyl-3,5-dimethoxybenzyloxycarbonyl,benzhydryloxycarbonyl, t-butyloxycarbonyl, diisopropylmethoxycarbonyl,isopropyloxycarbonyl, ethoxycarbonyl, methoxycarbonyl, allyloxycarbonyl,2,2,2,-trichloroethoxycarbonyl, phenoxycarbonyl, 4-nitrophenoxycarbonyl,fluorenyl-9-methoxycarbonyl, cyclopentyloxycarbonyl,adamantyloxycarbonyl, cyclohexyloxycarbonyl, phenylthiocarbonyl and thelike; alkyl groups such as benzyl, triphenylmethyl, benzyloxymethyl andthe like; and silyl groups such as trimethylsilyl and the like.Preferred suitable nitrogen protecting groups are formyl, acetyl,methyloxycarbonyl, benzoyl, pivaloyl, t-butylacetyl, phenylsulfonyl,benzyl, t-butyloxycarbonyl (Boc) and benzyloxycarbonyl (Cbz).

As used herein the term “(C₁-C₄)alkyl” refers to a straight or branched,monovalent, saturated aliphatic chain of 1 to 4 carbon atoms andincludes, but is not limited to methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl and the like.

As used herein the term “(C₁-C₆)alkyl” refers to a straight or branched,monovalent, saturated aliphatic chain of 1 to 6 carbon atoms andincludes, but is not limited to methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, and the like. It isunderstood that the term “(C₁-C₄)alkyl” is included within thedefinition of “(C₁-C₆)alkyl”.

As used herein the term “(C₁-C₁₀)alkyl” refers to a straight orbranched, monovalent, saturated aliphatic chain of 1 to 10 carbon atomsand includes, but is not limited to methyl, ethyl, propyl, isopropyl,n-butyl, isobutyl, tertiary butyl, pentyl, isopentyl, hexyl,2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3-pentyl, 2-methyl-2-hexyl,octyl, 4-methyl-3-heptyl and the like. It is understood that the terms“(C₁-C₄)alkyl” and “(C₁-C₆)alkyl” are included within the definition of“(C₁-C₁₀)alkyl”.

As used herein the term “(C₁-C₂₀)alkyl” refers to a straight orbranched, monovalent, saturated aliphatic chain of 1 to 20 carbon atomsand includes, but is not limited to, methyl, ethyl, propyl, isopropyl,butyl, isobutyl, t-butyl, pentyl, isopentyl, hexyl, 3-methylpentyl,2-ethylbutyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl,n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl,n-nonadecyl, n-eicosyl and the like. It is understood that the terms“(C₁-C₄)alkyl”, “(C₁-C₆)alkyl”, and “(C₁-C₁₀)alkyl” are included withinthe definition of “(C₁-C₂₀)alkyl”.

As used herein, the terms “Me”, “Et”, “Pr”, “iPr”, “Bu” and “t-Bu” referto methyl, ethyl, propyl, isopropyl, butyl and tert-butyl respectively.

As used herein, the term “(C₁-C₄)alkoxy” refers to an oxygen atombearing a straight or branched, monovalent, saturated aliphatic chain of1 to 4 carbon atoms and includes, but is not limited to methyoxy,ethyoxy, n-propoxy, isopropoxy, n-butoxy, and the like.

As used herein the term “(C₁-C₆)alkoxy” refers to an oxygen atom bearinga straight or branched, monovalent, saturated aliphatic chain of 1 to 6carbon atoms and includes, but is not limited to methoxy, ethoxy,n-propoxy, isopropoxy, n-butoxy, n-pentoxy, n-hexoxy, and the like.

As used herein, the term “(C₁-C₆)alkyl(C₁-C₆)alkoxy” refers to astraight or branched, monovalent, saturated aliphatic chain of 1 to 6carbon atoms which has a (C₁-C₆)alkoxy group attached to the aliphaticchain.

As used herein, the terms “Halo”, “Halide” or “Hal” refer to a chlorine,bromine, iodine or fluorine atom, unless otherwise specified herein.

As used herein the term “(C₂-C₆)alkenyl” refers to a straight orbranched, monovalent, unsaturated aliphatic chain having from two to sixcarbon atoms. Typical C₂-C₆ alkenyl groups include ethenyl (also knownas vinyl), 1-methylethenyl, 1-methyl-1-propenyl, 1-butenyl, 1-hexenyl,2-methyl-2-propenyl, 1-propenyl, 2-propenyl, 2-butenyl, 2-pentenyl, andthe like.

As used herein, the term “aryl” refers to a monovalent carbocyclic groupcontaining one or more fused or non-fused phenyl rings and includes, forexample, phenyl, 1- or 2-naphthyl, 1,2-dihydronaphthyl,1,2,3,4-tetrahydronaphthyl, and the like. The term “substituted aryl”refers to an aryl group substituted with one or two moieties chosen fromthe group consisting of halogen, hydroxy, cyano, nitro, (C₁-C₆)alkyl,(C₁-C₄)alkoxy, (C₁-C₆)alkyl(C₃-C₁₀)cycloalkyl, (C₁-C₆)alkylaryl,(C₁-C₆)alkoxycarbonyl, protected carboxy, carboxymethyl, hydroxymethyl,amino, aminomethyl, or trifluoromethyl.

As used herein, the term “(C₁-C₆)alkylaryl” refers to a straight orbranched, monovalent, saturated aliphatic chain of 1 to 6 carbon atomswhich has an aryl group attached to the aliphatic chain. Included withinthe term “C₁-C₆ alkylaryl” are the following:

and the like.

As used herein, the term “aryl(C₁-C₆)alkyl” refers to an aryl groupwhich has a straight or branched, monovalent, saturated aliphatic chainof 1 to 6 carbon atoms attached to the aryl group. Included within theterm “aryl(C₁-C₆)alkyl” are the following:

and the like.

As used herein the term “(C₃-C₁₀)cycloalkyl” refers to a saturatedhydrocarbon ring structure composed of one or more fused or unfusedrings containing from three to ten carbon atoms. Typical C₃-C₁₀cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, adamantanyl, and the like.

As used herein, the term “C₁-C₆ alkyl(C₃-C₁₀)cycloalkyl” refers to astraight or branched, monovalent, saturated aliphatic chain of 1 to 6carbon atoms which has a (C₃-C₁₀)cycloalkyl attached to the aliphaticchain. Included within the term “C₁-C₆ alkyl(C₃-C₁₀)cycloalkyl” are thefollowing:

the like.

As used herein, the term “(C₁-C₆) alkoxycarbonyl” refers to a carbonylgroup having a (C₁-C₆)alkyl group attached to the carbonyl carbonthrough an oxygen atom. Examples of this group include t-buoxycarbonyl,methoxycarbonyl, and the like.

As used herein the term “heterocycle” refers to a five- or six-memberedring, which contains one to four heteroatoms selected from the groupconsisting of oxygen, sulfur, and nitorgen. The remaining atoms of thering are recognized as carbon by those of skill in the art. Rings may besaturated or unsaturated. Examples of heterocycle groups includethiophenyl, furyl, pyrrolyl, imidazolyl, pyrrazolyl, thiazolyl,thiazolidinyl, isothiazolyl, oxazolyl, isoxazolyl, triazolyl,thiadiazolyl, oxadiazolyl, tetrazolyl, pyridyl, pyrimidyl, pyrazinyl,pyridiazinyl, triazinyl, imidazolyl, dihydropyrimidyl,tetrahydropyrimdyl, pyrrolidinyl, piperidinyl, piperazinyl,pyrazolidinyl, pyrimidinyl, imidazolidimyl, morpholinyl, pyranyl,thiomorpholinyl, and the like. The term “substituted heterocycle”represents a heterocycle group substituted with one or two moietieschosen from the group consisting of aryl, halogen, hydroxy, cyano,nitro, oxo, (C₁-C₆)alkyl, (C₁-C₄)alkoxy, C₁-C₆ alkyl(C₃-C₁₀)cycloalkyl,(C₁-C₆)alkylaryl, (C₁-C₆)alkoxycarbonyl, protected carboxy,carboxymethyl, hydroxymethyl, amino, aminomethyl, or trifluoromethyl.Further, the heterocycle group can be optionally fused to one or twoaryl groups to form a benzo-fused group. Examples of substitutedheterocycle include 1,2,3,4-tetrahydrodibenzeofuranyl,2-methylbezylfuranyl, and 3,5 dimethylisoxazolyl, and the like.

As used herein, the term “substituted tetrazole” refers to a tetrazolegroup substituted with a (C₁-C₄)alkyl moiety. Examples of substitutedtetrazole as used herein include:

and the like.

As used herein, the term “(C₁-C₆)allyl-heterocycle” refers to a straightor branched, monovalent, saturated aliphatic chain of 1 to 6 carbonatoms bearing a heterocycle group. Further, as used herein, the term“(C₁-C₆)alkyl-(substituted)heterocycle” refers to a straight orbranched, monovalent, saturated aliphatic chain of 1 to 6 carbon atomsbearing a substituted heterocycle group.

As used herein, the term “(C₁-C₆)alkyltetrazole” refers to a straight orbranched, monovalent, saturated aliphatic chain of 1 to 6 carbon atomsbearing a tetrazole group.

As used herein the term “N,N—C₁-C₆ dialkylamine” refers to a nitrogenatom substituted with two straight or branched, monovalent, saturatedaliphatic chains of 1 to 6 carbon atoms. Included within the term“N,N—C₁-C₆ dialkylamine” are —N(CH₃)₂, —N(CH₂CH₃)₂, —N(CH₂CH₂CH₃)₂,—N(CH₂CH₂CH₂CH₃)₂, and the like.

As used herein the term “C₁-C₆alkyl-N,N—C₁-C₆ dialkylamine” refers tostraight or branched, monovalent, saturated aliphatic chain of 1 to 6carbon atoms which has an N,N—C₁-C₆ dialkylamine attached to thealiphatic chain. Included within the term “C₁-C₆ alkyl-N,N—C₁-C₆dialkylamine” are the following:

and the like.

As used herein the term “(C₁-C₆)alkyl-pyrrolidine” refers to a straightor branched, monovalent, saturated aliphatic chain of 1 to 6 carbonatoms which has a pyrrolidine attached to the aliphatic chain. Includedwithin the scope of the term “(C₁-C₆)alkyl-pyrrolidine” are thefollowing:

and the like.

As used herein the term “(C₁-C₆)alkyl-piperidine” refers to a straightor branched, monovalent, saturated aliphatic chain of 1 to 6 carbonatoms which has a piperidine attached to the aliphatic chain. Includedwithin the scope of the term “(C₁-C₆)alkyl-piperidine” are thefollowing:

and the like.

As used herein the term “(C₁-C₆)alkyl-morpholine” refers to a straightor branched, monovalent, saturated aliphatic chain of 1 to 6 carbonatoms which has a morpholine attached to the aliphatic chain. Includedwithin the scope of the term “C₁-C₆ alkyl-morpholine” are the following:

and the like.

The designation

refers to a bond that protrudes forward out of the plane of the page.

The designation

refers to a bond that protrudes backward out of the plane of the page.

As used herein the term “iGluR₅” refers to the kainate ionotropicglutamate receptor, subtype 5, of the larger class of excitatory aminoacid receptors.

As used herein the term “migraine” refers a disorder of the nervoussystem characterized by recurrent attacks of head pain (which are notcaused by a structural brain abnormalitiy such as those resulting fromtumor or stroke), gasrointestinal disturbances, and possiblyneurological symptoms such as visual distortion. Characteristicheadaches of migraine usually last one day and are commonly accompaniedby nausea, emesis, and photophobia.

Migraine may represent a “chronic” condition, or an “acute” episode. Theterm “chronic”, as used herein, means a condition of slow progress andlong continuance. As such, a chronic condition is treated when it isdiagnosed and treatment continued throughout the course of the disease.Conversely, the term “acute”means an exacerbated event or attack, ofshort course, followed by a period of remission. Thus, the treatment ofmigraine contemplates both acute events and chronic conditions. In anacute event, compound is administered at the onset of symptoms anddiscontinued when the symptoms disappear. As described above, a chroniccondition is treated throughout the course of the disease.

As used herein the term “patient” refers to a mammal, such a mouse,gerbil, guinea pig, rat, dog or human. It is understood, however, thatthe preferred patient is a human.

The term “iGluR₅ receptor antagonist” or “iGluR₅ antagonist”, as usedherein, refers to those excitatory amino acid receptor antagonists whichbind to, and antagonize the activity of, the iGluR₅ kainate receptorsubtype. As a preferred embodiment, the present invention furtherprovides selective iGluR₅ receptor antagonists. “Selective iGluR₅receptor antagonist” or “selective iGluR₅ antagonist” as used herein,includes those excitatory amino acid receptor antagonists whichselectively bind to, and antagonize, the iGluR₅ kainate receptorsubtype, relative to the iGluR₂ AMPA receptor subtype. Preferably the“selective iGluR₅ antagonists” for use according to the methods of thepresent invention have a binding affinity at least 10 fold greater foriGluR₅ than for iGluR₂, more preferably at least 100 fold greater. WO98/45270 provides examples of selective iGluR₅ receptor antagonists anddiscloses methods for synthesis.

As used herein, the terms “treating”, “treatment”, or “to treat” eachmean to alleviate symptoms, eliminate the causation of resultantsymptoms either on a temporary or permanent basis, and to prevent, slowthe appearance, or reverse the progression or severity of resultantsymptoms of the named disorder. As such, the methods of this inventionencompass both therapeutic and prophylactic administration.

As used herein the term “effective amount” refers to the amount or doseof the compound, upon single or multiple dose administration to thepatient, which provides the desired effect in the patient underdiagnosis or treatment. An effective amount can be readily determined bythe attending diagnostician, as one skilled in the art, by the use ofknown techniques and by observing results obtained under analogouscircumstances. In determining the effective amount or dose of compoundadministered, a number of factors are considered by the attendingdiagnostician, including, but not limited to: the species of mammal; itssize, age, and general health; the degree of involvement or the severityof the disease involved; the response of the individual patient; theparticular compound administered; the mode of administration; thebioavailability characteristics of the preparation administered; thedose regimen selected; the use of concomitant medication; and otherrelevant circumstances.

A typical daily dose will contain from about 0.01 mg/kg to about 100mg/kg of each compound used in the present method of treatment.Preferably, daily doses will be about 0.05 mg/kg to about 50 mg/kg, morepreferably from about 0.1 mg/kg to about 25 mg/kg.

Oral administration is a preferred route of administering the compoundsemployed in the present invention whether administered alone, or as acombination of compounds capable of acting as an iGluR₅ receptorantagonist. Oral administration, however, is not the only route, noreven the only preferred route. Other preferred routes of administrationinclude transdermal, percutaneous, pulmonary, intravenous,intramuscular, intranasal, buccal, sublingual, or intrarectal routes.Where the iGluR₅ receptor antagonist is administered as a combination ofcompounds, one of the compounds may be administered by one route, suchas oral, and the other may be administered by the transdermal,percutaneous, pulmonary, intravenous, intramuscular, intranasal, buccal,sublingual, or intrarectal route, as particular circumstances require.The route of administration may be varied in any way, limited by thephysical properties of the compounds and the convenience of the patientand the caregiver.

The compounds employed in the present invention may be administered aspharmceutical compositions and, therefore, pharmaceutical compositionsincorporating compounds of Formula I or Formula II are importantembodiments of the present invention. Such compositions may take anyphysical form that is pharmaceutically acceptable, but orallyadministered pharmaceutical compositions are particularly preferred.Such pharmaceutical compositions contain, as an active ingredient, aneffective amount of a compound of Formula I or Formula II, including thepharmaceutically acceptable salts, prodrugs, and hydrates thereof, whicheffective amount is related to the daily dose of the compound to beadministered. Each dosage unit may contain the daily dose of a givencompound, or may contain a fraction of the daily dose, such as one-halfor one-third of the dose. The amount of each compound to be contained ineach dosage unit depends on the identity of the particular compoundchosen for the therapy, and other factors such as the indication forwhich it is given. The pharmaceutical compositions of the presentinvention may be formulated so as to provide quick, sustained, ordelayed release of the active ingredient after administration to thepatient by employing well known procedures.

Compositions are preferably formulated in a unit dosage form, eachdosage containing from about 1 to about 500 mg of each compoundindividually or in a single unit dosage form, more preferably about 5 toabout 300 mg (for example 25 mg). The term “unit dosage form” refers toa physically discrete unit suitable as unitary dosages for a patient,each unit containing a predetermined quantity of active materialcalculated to produce the desired therapeutic effect, in associationwith a suitable pharmaceutical carrier, diluent, or excipient.

The inert ingredients and manner of formulation of the pharmaceuticalcompositions are conventional. The usual methods of formulation used inpharmaceutical science may be used here. All of the usual types ofcompositions may be used, including tablets, chewable tablets, capsules,solutions, parenteral solutions, intranasal sprays or powders, troches,suppositories, transdermal patches and suspensions. In general,compositions contain from about 0.5% to about 50% of the compounds intotal, depending on the desired doses and the type of composition to beused. The amount of the compound, however, is best defined as the“effective amount”, that is, the amount of each compound which providesthe desired dose to the patient in need of such treatment. The activityof the compounds employed in the present invention do not depend on thenature of the composition, hence, the compositions are chosen andformulated solely for convenience and economy.

Capsules are prepared by mixing the compound with a suitable diluent andfilling the proper amount of the mixture in capsules. The usual diluentsinclude inert powdered substances such as starches, powdered celluloseespecially crystalline and microcrystalline cellulose, sugars such asfructose, mannitol and sucrose, grain flours, and similar ediblepowders.

Tablets are prepared by direct compression, by wet granulation, or bydry granulation. Their formulations usually incorporate diluents,binders, lubricants and disintegrators as well as the compound. Typicaldiluents include, for example, various types of starch, lactose,mannitol, kaolin, calcium phosphate or sulfate, inorganic salts such assodium chloride and powdered sugar. Powdered cellulose derivatives arealso useful. Typical tablet binders are substances such as starch,gelatin and sugars such as lactose, fructose, glucose and the like.Natural and synthetic gums are also convenient, including acacia,alginates, methylcellulose, polyvinylpyrrolidine and the like.Polyethylene glycol, ethylcellulose and waxes can also serve as binders.

Tablets are often coated with sugar as a flavor and sealant. Thecompounds may also be formulated as chewable tablets, by using largeamounts of pleasant-tasting substances such as mannitol in theformulation, as is now well-established practice. Instantly dissolvingtablet-like formulations are also now frequently used to assure that thepatient consumes the dosage form, and to avoid the difficulty inswallowing solid objects that bothers some patients.

A lubricant is often necessary in a tablet formulation to prevent thetablet and punches from sticking in the die. The lubricant is chosenfrom such slippery solids as talc, magnesium and calcium stearate,stearic acid and hydrogenated vegetable oils.

Tablet disintegrators are substances which swell when wetted to break upthe tablet and release the compound. They include starches, clays,celluloses, algins and gums. More particularly, corn and potatostarches, methylcellulose, agar, bentonite, wood cellulose, powderednatural sponge, cation-exchange resins, alginic acid, guar gum, citruspulp and carboxymethylcellulose, for example, may be used, as well assodium lauryl sulfate.

Enteric formulations are often used to protect an active ingredient fromthe strongly acid contents of the stomach. Such formulations are createdby coating a solid dosage form with a film of a polymer which isinsoluble in acid environments, and soluble in basic environments.Exemplary films are cellulose acetate phthalate, polyvinyl acetatephthalate, hydroxypropyl methylcellulose phthalate and hydroxypropylmethylcellulose acetate succinate.

When it is desired to administer the compound as a suppository, theusual bases may be used. Cocoa butter is a traditional suppository base,which may be modified by addition of waxes to raise its melting pointslightly. Water-miscible suppository bases comprising, particularly,polyethylene glycols of various molecular weights are in wide use, also.

Transdermal patches have become popular recently. Typically theycomprise a resinous composition in which the drugs will dissolve, orpartially dissolve, which is held in contact with the skin by a filmwhich protects the composition. Many patents have appeared in the fieldrecently. Other, more complicated patch compositions are also in use,particularly those having a membrane pierced with innumerable poresthrough which the drugs are pumped by osmotic action.

The following table provides an illustrative list of formulationssuitable for use with the compounds employed in the present invention.The following is provided only to illustrate the invention and shouldnot be interpreted as limiting the present invention in any way.Formulation 1 Hard gelatin capsules are prepared using the followingingredients: Quantity (mg/capsule) Active Ingredient 250 Starch, dried200 Magnesium stearate  10 Total 460 mg

The above ingredients are mixed and filled into hard gelatin capsules in460 mg quantities. Formulation 2 A tablet is prepared using theingredients below: Quantity (mg/tablet) Active Ingredient 250 Cellulose,microcrystalline 400 Silicon dioxide, fumed  10 Stearic acid  5 Total665 mg

The components are blended and compressed to form tablets each weighing665 mg. Formulation 3 An aerosol solution is prepared containing thefollowing components: Weight % Active Ingredient 0.25 Ethanol 29.75Propellant 22 70.00 (Chlorodifluoromethane) Total 100.00

The active compound is mixed with ethanol and the mixture added to aportion of the Propellant 22, cooled to −30° C. and transferred to afilling device. The required amount is then fed to a stainless steelcontainer and diluted with the remainder of the propellant. The valveunits are then fitted to the container. Formulation 4 Tablets eachcontaining 60 mg of active ingredient are made as follows: ActiveIngredient 60.0 mg Starch 45.0 mg Microcrystalline cellulose 35.0 mgPolyvinylpyrrolidone  4.0 mg Sodium carboxymethyl starch  4.5 mgMagnesium stearate  0.5 mg Talc  1.0 mg Total  150 mg

The active ingredient, starch, and cellulose are passed through a No. 45mesh U.S. sieve and mixed thoroughly. The solution ofpolyvinylpyrrolidone is mixed with the resultant powders which are thenpassed through a No. 14 mesh U.S. sieve. The granules so produced aredried at 50° C. and passed through a No. 18 mesh U.S. sieve. The sodiumcarboxymethyl starch, magnesium stearate, and talc, previously passedthrough a No. 60 mesh U.S. sieve, are then added to the granules which,after mixing, are compressed on a tablet machine to yield tablets eachweighing 150 mg. Formulation 5 Capsules each containing 80 mg medicamentare made as follows: Active Ingredient  80 mg Starch  59 mgMicrocrystalline cellulose  59 mg Magnesium stearate  2 mg Total 200 mg

The active ingredient, cellulose, starch, and magnesium stearate areblended, passed through a No. 45 sieve, and filled into hard gelatincapsules in 200 mg quantities. Formulation 6 Suppositories eachcontaining 225 mg of active ingredient may be made as follows: ActiveIngredient   225 mg Saturated fatty acid glycerides 2,000 mg Total 2,225mg

The active ingredient is passed through a No. 60 mesh U.S. sieve andsuspended in the saturated fatty acid glycerides previously melted usingthe minimum heat necessary. The mixture is then poured into asuppository mold of nominal 2 g capacity and allowed to cool.Formulation 7 Suspensions each containing 50 mg of medicament per 5 mldose are made as follows: Active Ingredient   50 mg Sodium carboxymethylcellulose   50 mg Syrup 1.25 ml Benzoic acid solution 0.10 ml Flavorq.v. Color q.v. Purified water to total   5 ml

The medicament is passed through a No. 45 mesh U.S. sieve and mixed withthe sodium carboxymethyl cellulose and syrup to form a smooth paste. Thebenzoic acid solution, flavor and color are diluted with some of thewater and added, with stirring. Sufficient water is then added toproduce the required volume. Formulation 8 An intravenous formulationmay be prepared as follows: Active Ingredient 100 mg Mannitol 100 mg 5 NSodium hydroxide 200 ml Purified water to total  5 ml

It is understood by one of ordinary skill in the art that the proceduresas described above can also be readily applied to a method of treatingneurological disorders or neurodegenerative conditions, particularlypain and migraine, comprising administering to a patient an effectiveamount of a compound of Formula I or Formula II.

Compounds of Formula I and Formula II can be prepared, for example, byfollowing the procedures set forth in the Schemes below. Allsubstituents, unless otherwise indicated, are previously defined. Thereagents and starting materials are readily available to one of ordinaryskill in the art. For example, certain starting materials can beprepared by one of ordinary skill in the art following proceduresdisclosed in U.S. Pat. No. 5,356,902 (issued Oct. 18, 1994); U.S. Pat.No. 5,446,051 (issued Aug. 29, 1995); and U.S. Pat. No. 5,670,516(issued Sep. 23, 1997) the entire contents, all of which, are hereinincorporated by reference. Certain reagents may be prepared by one ofordinary skill in the art following procedures disclosed by Demange etal., Tetrahedron Lett., 39, 1169-1172 (1998).

Scheme I provides procedures for the synthesis of compounds of Formula Iwherein R¹ and R² each independently represent fluorine.

In Scheme I, Step A, the compound of structure (1) (PG is a suitablenitrogen protecting group as defined hereinabove, with methoxyl carbonylbeing preferred) is treated under standard conditions with a compound offormula Lg-Hal wherein Lg is a suitable leaving group and Hal representsa chloro, bromo or iodo atom, to provide structure (2). Examples ofLg-Hal include m-nitrobenzenesulfonyl chloride, p-nitrobenzenesulfonylchloride, p-bromobenzenesulfonyl chloride, p-toluenesulfonyl chloride,benzenesulfonyl chloride, methanesulfonyl chloride,trifluoromethanesulfonyl chloride, and the like. For example, a solutionof6-hydroxymethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate,dissolved in a suitable organic solvent such as dichloromethane andcooled to 0° C., is treated with an excess of a suitable organic base,such as triethylamine, followed by about 1 to 2 equivalents ofp-toluenesulfonyl chloride. The reaction mixture is warmed to roomtemperature and stirred for about 5 to 20 hours. The compound ofstructure (2) is then isolated using standard procedures. For example,the reaction mixture is washed with water, the organic layer separatedand dried over anhydrous sodium sulfate, filtered, and concentratedunder vacuum to provide crude compound (2). Column chromatography canthen be performed on silica gel with a suitable eluent such as 10-50%ethyl acetate/hexane to provide the purified compound (2).

In Scheme I, Step B, compound (2) is treated under standard conditionswith a pyrrolidine of structure (3) to provide the compound of structure(5). Alternatively, compound (4) can be treated under the sameconditions to provide the compound of strucure (5). For example,compound (2) of Step A above, or alternatively6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate,compound (4), is mixed with about 1-1.5 equivalents of4-hydroxy-L-proline ethyl ester and 1-1.5 equivalents of potassiumcarbonate and heated at reflux in a suitable solvent such asacetonitrile for about 60-70 hours. The reaction mixture is cooled toroom temperature and solvents removed under vacuum. Compound (5) is thenisolated using standard procedures such as extraction techniques. Forexample, the reaction mixture is partitioned between water and anorganic solvent such as diethyl ether, and the aqueous layer extracted2-6 times with diethyl ether. The organic layers are combined, driedover anhydrous sodium sulfate, filtered, and concentrated under vacuumto provide compound (5). Compound (5) can then be purified bychromatography on silica gel with a suitable eluent such as ethylacetate/hexanes or methanol/chloroform.

In Scheme I, Step C, treatment of compound (5) with standard oxidizingconditions provides the ketone of structure (6). For example, compound(5) can be added to a mixture of oxalyl chloride and DMSO, followed byaddition of triethylamine and warming the reaction to room temperature.The reaction mixture is partitioned between water and an organic solventsuch as methylene chloride, and the aqueous layer extracted 2-6 timeswith methylene chloride. The organic layers are combined, dried overanhydrous sodium sulfate, filtered, and concentrated under vacuum toprovide compound (6). Compound (6) can then be purified using standardprocedures such as chromatography on silica gel with a suitable eluentsuch as ethyl acetate/hexanes or methanol/chloroform.

In Scheme I, Step D, the compound of strucure (6) is treated withdiethylamino sulfur trifluoride to yield the intermediate of structure(7) wherein for purposes of the present scheme, R⁴ and R² each representflurorine. For example, to a mixture of compound (6), cooled to about−78° C. in CH₂Cl₂, is added dropwise diethylamino sulfur trifluoride.The reaction is allowed to warm to room temperature, stirred for about48 hours, and quenched by addition of MeOH. The compound of strucure (7)wherein for purposes of the present scheme, R⁴ and R² each representflurorine, is then concentrated under standard conditions. For example,compound (7) is first concentrated under vacuum, then the residuepartitioned between CH₂Cl₂ and aqueous NaHCO₃. The aqueous layer is thenextracted with CH₂Cl₂ and the combined organics dried over MgSO4,filtered, and concentrated under vacuum to provide the concentratedcompound (7) wherein for purposes of the present scheme, R⁴ and R² eachrepresent flurorine. This material may then be purified by techniqueswell known in the art such as chromatography on silica gel with asuitable eluent, such as 25-50% EtOAc/hexane to provide the purifiedcompound of structure (7).

In Scheme I, Step E, compound (7) is deprotected under standardconditions well known in the art to provide the compound of Formula Ia,wherein R⁴ and R² both represent fluorine. For example, when Pg is amethoxycarbonyl protecting group, compound (7) is dissolved in asuitable organic solvent such as dichloromethane under an atmosphere ofnitrogen and treated with trimethylsilyl iodide. The reaction mixture isallowed to warm to room temperature and stirred for about 10-20 hours.The reaction is quenched by addition of saturated aqueous NaHCO₃. Theaqueous layer is then extracted 2-6 times with dichloromethane. Theorganics are then combined, washed with a 1N solution of sodiumthiosulfate, dried over magnesium sulfate, filtered, and concentrated invacuo to provide the compound of Formula Ia, wherein R⁴ and R² bothrepresent fluorine. This material can then be purified by chromatographyon silica gel with a suitable eluent such as methanol/dichloromethane,to provide the purified compound of Formula Ia, wherein R⁴ and R² bothrepresent fluorine.

In Scheme I, Step F, the compound of Formula Ia, from Step E ishydrolyzed to the compound of Formula I, wherein R¹ and R² bothrepresent fluorine, under conditions well known in the art. For example,the compound of Formula Ia is dissolved in a suitable organic solventsuch as methanol, and treated with an excess of a suitable base.Examples of suitable bases include aqueous lithium hydroxide, sodiumhydroxide, potassium hydroxide, and the like, with lithium hydroxidebeing preferred. The reaction is stirred for about 10-20 hours. Thereaction mixture is then neutralized to pH 6 with 1N HCl andconcentrated under vacuum to provide the crude compound of Formula I,wherein R¹ and R² both represent fluorine. This material can then bepurified by techniques well known in the art, such as cation exchangechromatography eluting with THF/water followed by 10% pyridine in waterto provide the purified compound of Formula I, wherein R¹ and R² bothrepresent fluorine.

In Scheme I, Step G, compound (7) is deprotected and hydrolyzedconcomitantly to provide the compound of Formula I, wherein R¹ and R²both represent fluorine. For example, a solution of compound (7)dissolved in 5N HCl is heated to reflux (90-95° C.) for about 15-20hours. The reaction mixture is then allowed to cool to room temperatureand concentrated in vacuo to provide the compound of Formula I, whereinR¹ and R² both represent fluorine. The compound of Formula I can then bepurified by techniques well known in the art, such as cation exchangechromatography eluting with THF/water followed by 10% pyridine in waterto provide the purified compound of Formula I, wherein R¹ and R² bothrepresent fluorine.

In Scheme I, Step H, the compound of Formula I from Step F or G above,can be esterified under conditions well known in the art, to provide thecompound of Formula Ia, wherein R⁴ and R² both represent fluorine. Forexample, the compound of Formula I is dissolved in a suitable organicsolvent such as ethanol, and treated with an excess of a suitable acid.Examples of suitable acids include gaseous hydrochloric acid, aqueoussulfuric acid, p-toluene sulfonic acid, and the like with gaseoushydrochloric acid being preferred. The reaction mixture is heated toreflux (78-85° C.) for about 15-25 hours. The reaction mixture isconcentrated under vacuum to provide the crude compound of Formula Ia,wherein R⁴ and R² both represent fluorine. This material can then bepurified by techniques well known in the art, such as cation exchangechromatography eluting with ethanol/water followed by 2N ammonia inethanol to provide the purified compound of Formula Ia, wherein R⁴ andR² both represent fluorine.

Scheme II provides procedures for the synthesis of compounds of FormulaI, wherein R¹ is fluorine and R² is hydrogen.

In Scheme II, Step B, the compound of structure (4) (PG is a suitablenitrogen protecting group as defined hereinabove, with methoxyl carbonylbeing preferred) is treated under standard conditions with a pyrrolidineof structure (8) (wherein for purposes of the present scheme R⁴ isfluorine and R² is hydrogen) to provide the compound of structure (9).For example,6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate ismixed with about 1-1.5 equivalents of trans-4-fluoro-L-proline ethylester (prepared by one of ordinary skill in the art following theprocedures as disclosed in Tetrahedron Lett., 39, 1169-1172 (1998)) andabout 1-1.5 equivalents of potassium carbonate and heated at reflux in asuitable solvent such as acetonitrile for about 60-70 hours. Thereaction mixture is cooled to room temperature and then loaded onto anSCX-cation exchange cartridge. Following elution with MeOH, then 2 MNH3/MeOH, compound (9) can then be purified by chromatography on silicagel with a suitable eluent such as ethyl acetate/hexanes ormethanol/chloroform.

In Scheme II, Step E, compound (9) is deprotected under standardconditions well known in the art as described previously in Scheme I,Step E to provide the compound of Formula Ia, wherein for purposes ofthe present scheme R⁴ is fluorine and R² is hydrogen. This material canthen be concentrated and purified, again by procedures well known in theart as described in Scheme I, Step E to provide the purified compound ofFormula Ia, wherein R⁴ is fluorine and R² is hydrogen.

In Scheme II, Step P, following the procedures as described in Scheme I,Step P, the compound of Formula Ia, wherein for purposes of the presentscheme R⁴ is fluorine and R² is hydrogen, is hydrolyzed to the compoundof Formula I under conditions well known in the art. This material canthen be concentrated and purified by techniques well known in the art asdescribed in Scheme I, Step F, to provide the purified compound ofFormula I, wherein for purposes of the present scheme R¹ is fluorine andR² is hydrogen.

In Scheme II, Step G, following the procedures as described in Scheme I,Step G, compound (9) is deprotected and hydrolyzed concomitantly toprovide the compound of Formula I, wherein for purposes of the presentscheme R¹ is fluorine and R² is hydrogen. The compound of Formula I canthen be concentrated and purified by techniques well known in the art asdescribed in Scheme I, Step G, to provide the purified compound ofFormula I, wherein R¹ is fluorine and R² is hydrogen.

In Scheme II, Step H, following the procedures as described in Scheme I,Step H, the compound of Formula I, whrerein for purposes of the presentscheme R¹ is fluorine and R² is hydrogen, can be esterified underconditions well known in the art, to provide the compound of Formula Ia,wherein R⁴ is fluorine and R² is hydrogen. This material can then beconcentrated and purified by techniques well known in the art asdescribed in Scheme I, Step H, to provide the purified compound ofFormula Ia, wherein R⁴ is fluorine and R² is hydrogen.

Scheme III provides procedures for the synthesis of compounds of FormulaI wherein R¹ represents chlorine, bromine, or iodine, and R² representshydrogen.

In Scheme III, Step C, the intermediate of structure (5) (prepared asdescribed in Scheme I above) is treated under standard conditions with ahalogenating source to provide the compound of structure (10), whereinR⁴ for the purposes of this scheme represents chlorine, bromine, oriodine and R² represents hydrogen. For example, compound (5) is mixedwith about 1-1.5 equivalents of a solution of triphenylphosphine andCCl₄ and stirred at room temperature in a suitable solvent such asmethylene chloride for about 20 hours. The compound of structure (10) isthen isolated using standard procedures. For example, the reactionmixture is washed with water, the organic layer separated and dried overanhydrous sodium sulfate, filtered, and concentrated under vacuum toprovide crude compound (10), wherein R⁴ represents chlorine, bromine, oriodine and R² represents hydrogen. Column chromatography can then beperformed on silica gel with a suitable eluent such as 10-50% ethylacetate/hexane to provide the purified compound (10), wherein R⁴represents chlorine, bromine, or iodine and R² represents hydrogen.

In Scheme III, Step E, following the procedures as described in SchemeI, Step E, compound (10) from Scheme Im, Step C is deprotected understandard conditions well known in the art to provide the compound ofFormula Ia, wherein for the purposes of the present scheme R⁴ representschlorine, bromine, or iodine and R² represents hydrogen. The materialcan then be concentrated and purified by procedures well known in theart as described in Scheme I, Step E, to provide the purified compoundof Formula Ia, wherein R⁴ represents chlorine, bromine, or iodine and R²represents hydrogen.

In Scheme III, Step F, following the procedures as described in SchemeI, Step F, the compound of Formula Ia, wherein for the purposes of thepresent scheme R⁴ represents chlorine, bromine, or iodine and R²represents hydrogen, is hydrolyzed to the compound of Formula L whereinR¹ represents chlorine, bromine, or iodine and R² represents hydrogen,under conditions well known in the art. This material can then beconcentrated and purified by techniques well known in the art asdescribed in Scheme I, Step F, to provide the purified compound ofFormula I, wherein R¹ represents chlorine, bromine, or iodine and R²represents hydrogen.

In Scheme III, Step G, following the procedures as described in SchemeI, Step G, compound (10), wherein for the purposes of the present schemeR⁴ represents chlorine, bromine, or iodine and R² represents hydrogen,is deprotected and hydrolyzed concomitantly to provide the compound ofFormula I, wherein R¹ represents chlorine, bromine, or iodine and R²represents hydrogen. The compound of Formula I can then be concentratedand purified by techniques well known in the art as described in SchemeI, Step G, to provide the purified compound of Formula I, wherein forthe purposes of the present scheme R¹ represents chlorine, bromine, oriodine and R² represents hydrogen.

In Scheme III, Step H, following the procedures as described in SchemeI, Step H, the compound of Formula I, wherein for the purposes of thepresent scheme R¹ represents chlorine, bromine; or iodine and R²represents hydrogen, can be esterified, under conditions well known inthe art, to provide the compound of Formula Ia, wherein R⁴ representschlorine, bromine, or iodine and R² represents hydrogen. This materialcan then be concentrated and purified by techniques well known in theart as described in Scheme I, Step H to provide the purified compound ofFormula Ia, wherein for purposes of the present scheme R⁴ representschlorine, bromine, or iodine and R² represents hydrogen.

Scheme IV provides procedures for the synthesis of compounds of FormulaI wherein R¹ represents SR³, R² represents hydrogen, and R³ representstetrazole, substituted tetrazole, or triazole.

In Scheme IV, Step C, the intermediate (5) (prepared as described inScheme I) is treated under standard conditions with a compound offormula Lg-Hal, wherein LG is a suitable leaving group and Halrepresents a chloro, bromo or iodo atom, to provide the compound ofstructure (11). Alternatively (5) may be treated under standardconditions with a brominating source, providing intermediate (11a). Forexample, a solution of compound (5), dissolved in a suitable organicsolvent such as dichloromethane and cooled to 0° C., is treated with anexcess of a suitable organic base, such as triethylamine, followed byabout 1 to 2 equivalents of a compound of formula Lg-Hal. Examples ofLg-Hal include m-nitrobenzenesulfonyl chloride, p-nitrobenzenesulfonylchloride, p-bromobenzenesulfonyl chloride, p-toluenesulfonyl chloride,benzenesulfonyl chloride, methanesulfonyl chloride,trifluoromethanesulfonyl chloride, and the like. The reaction mixture iswarmed to room temperature and stirred for about 5 to 20 hours. Thecompound (11) is then isolated using standard procedures. For example,the reaction mixture is washed with water, the organic layer separatedand dried over anhydrous sodium sulfate, filtered, and concentratedunder vacuum to provide crude compound (11). Column chromatography canthen be performed on silica gel with a suitable eluent such as 10-50%ethyl acetate/hexane to provide the purified compound (11).

Alternatively, compound (5) is added to a solution of about 1.5equivalents of triphenylphosphine and about 1.5 equivalents of brominepremixed in a suitable solvent such as methylene chloride. The reactionis further treated with approximately 2 equivalents of pyridine, thenstirred for about 20 hours. The compound of structure (11a) is thenisolated using standard procedures. For example, the reaction mixture iswashed with water, the organic layer separated and dried over anhydroussodium sulfate, filtered, and concentrated under vacuum to provide crudecompound (11a). Column chromatography can then be performed on silicagel with a suitable eluent such as 10-50% ethyl acetate/hexane toprovide the purified compound of structure (11a).

In Scheme IV, Step D, compound (11) or compound (11a) is treated with acompound of structure (12), wherein Y represents CH or N, in thepresence of potassium carbonate to give the compound of structure (13),wherein for purposes of the present scheme R² is hydrogen, R⁴ is SR⁷,and R⁷ represents tetrazole or triazole. For example, a solution of(11), about 3 equivalents of thiotetrazole, and about 1.5 equivalents ofpotassium carbonate in acetonitrile is heated to 80° C. for about 60hours. The compound (13) is then isolated using standard procedures. Forexample, the reaction mixture is washed with water, the organic layerseparated and dried over anhydrous sodium sulfate, filtered, andconcentrated under vacuum to provide crude compound (13), wherein forpurposes of the present scheme R² is hydrogen, R⁴ is SR⁷, and R⁷represents tetrazole or triazole. Column chromatography can then beperformed on silica gel with a suitable eluent such as 10-50% ethylacetate/hexane to provide the purified compound (13).

This intermediate can be deprotected as describe infra, oralternatively, where R⁷ represents tetrazole, the compound (13) may befurther alkylated with a compound of formula Z-halo, (wherein Zrepresents (C₁-C₄)alkyl and halo represents a chloro, bromo or iodoatom) to provide a compound of structure (14a) or (14b) below:

wherein Z represents a (C₁-C₄)alkyl group.

For example, a solution of compound (13), wherein R⁷ representstetrazole, dissolved in a suitable organic solvent such as THF andcooled to 0° C., is treated with an excess of NaH, followed byiodomethane. The compound (14), wherein R² is hydrogen, R⁴ is SR⁷, andR⁷ represents a substituted tetrazole, is then isolated using standardprocedures. For example, the reaction mixture is washed with water, theorganic layer separated and dried over anhydrous sodium sulfate,filtered, and concentrated under vacuum to provide the crude mixture ofcompounds (14a) and (14b) wherein R² is represented by hydrogen, R⁴ isrepresented by SR⁷, and R⁷ represents a substituted tetrazole (Zrepresents a (C₁-C₄)alkyl group). Column chromatography can then beperformed on silica gel with a suitable eluent such as 10-50% ethylacetate/hexane to separate isomers (14a) and (14b), providing thepurified compound (14a) or (14b).

In Scheme IV, Step F, compound (13), or alternatively, compound (14(a)or (b)) (both as defined previously above) is deprotected under standardconditions well known in the art to provide the compound of Formula Ia,wherein R² is hydrogen, R⁴ is SR⁷, and R⁷ represents tetrazole,substituted tetrazole, or triazole. For example, when PG is amethoxycarbonyl protecting group, compound (14) is dissolved in asuitable organic solvent such as dichloromethane under an atmosphere ofnitrogen and treated with trimethylsilyl iodide. The reation mixture isallowed to warm to room temperature and stirred for about 10-20 hours.The reaction is quenched by addition of saturated aqueous NaHCO₃. Theaqueous layer is then extracted 2-6 times with dichloromethane. Theorganics are then combined, washed with a 1N solution of sodiumthiosulfate, dried over magnesium sulfate, filtered, and concentrated invacuo to provide the compound of Formula Ia, wherein R² is hydrogen, R⁴is SR⁷, and R⁷ represents tetrazole, substituted tetrazole, or triazole.The material can then be purified by chromatography on silica gel with asuitable eluent such as methanol/dichoromethane, to provide the purifiedcompound of Formula Ia, wherein R² is hydrogen, R⁴ is SR⁷, and R⁷represents tetrazole, substituted tetrazole, or triazole.

In Scheme IV, Step G, the compound of Formula Ia is hydrolyzed to thecompound of Formula I, wherein R² is hydrogen, R¹ is SR³, and R³represents tetrazole, substituted tetrazole, or triazole, underconditions well known in the art. For example, the compound of FormulaIa, wherein R² is hydrogen, R⁴ is SR⁷, and R⁷ represents tetrazole,substituted tetrazole, or triazole, is dissolved in a suitable organicsolvent such as methanol, and treated with an excess of a suitable base.Examples of suitable bases include aqueous lithium hydroxide, sodiumhydroxide, potassium hydroxide, and the like, with lithium hydroxidebeing preferred. The reaction is stirred for about 10-20 hours. Thereaction mixture is then neutralized to pH 6 with 1N HCl andconcentrated under vacuum to provide the crude compound of Formula I,wherein R² is hydrogen, R¹ is SR³, and R³ represents tetrazole,substituted tetrazole, or triazole. This material can then be purifiedby techniques well known in the art, such as cation exchangechromatography eluting with THF/water followed by 10% pyridine in waterto provide the purified compound of Formula I.

In Scheme IV, Step H, compound (13) or compound (14) (as describedpreviously in Scheme IV, Step D above) is deprotected and hydrolyzedconcomitantly to provide the compound of Formula I, wherein R² ishydrogen, R¹ is SR³, and R³ represents tetrazole, substituted tetrazole,or triazole. For example, a solution of compound (13) or compound (14)dissolved in 5N HCl is heated to reflux (90-95° C.) for about 15-20hours. The reaction mixture is then allowed to cool to room temperatureand concentrated in vacuo to provide the compound of Formula I, whereinR² is hydrogen, R¹ is SR³, and R³ represents tetrazole, substitutedtetrazole, or triazole. The compound of Formula I can then be purifiedby techniques well known in the art, such as cation exchangechromatography eluting with THF/water followed by 10% pyridine in waterto provide the purified compound of Formula L.

In Scheme IV, Step I, the compound of Formula I, wherein R² is hydrogen,R¹ is SR³, and R³ represents tetrazole, substituted tetrazole, ortriazole, can be esterified, under conditions well known in the art, toprovide the compound of Formula Ia, wherein R² is hydrogen, R⁴ is SR⁷,and R⁷ represents tetrazole, substituted tetrazole, or triazole. Forexample, the compound of Formula I is dissolved in a suitable organicsolvent such as ethanol, and treated with an excess of a suitable acid.Examples of suitable acids include gaseous hydrochloric acid, aqueoussulfuric acid, p-toluene sulfonic acid, and the like with gaseoushydrochloric acid being preferred. The reaction mixture is heated toreflux (78-85° C.) for about 15-25 hours. The reaction mixtureconcentrated under vacuum to provide the crude compound of Formula Ia,wherein R² is hydrogen, R⁴ is SR⁷, and R⁷ represents tetrazole,substituted tetrazole, or triazole. This material can then be purifiedby techniques well known in the art, such as cation exchangechromatography eluting with methanol/water followed by 2N ammonia inethanol to provide the purified compound of Formula Ia.

Scheme V provides procedures for the synthesis of compounds of FormulaI, wherein R¹ represents SR³, R² represents hydrogen, and R³ represents(C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂H.

In Scheme V, Step B, the intermediate (2) (prepared as described inScheme I) is treated under standard conditions with a compound offormula (15), wherein R² represents hydrogen, R⁴ represents SR⁷, and R⁷represents (C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂R⁸, to provide the compoundof structure (16). For example, a solution of compound (2), dissolved ina suitable organic solvent such as acetonitrile is treated with about1.4 equivalents of a compound of formula (15), such as ethyl 2S,4S,4-ethoxycarbonylmethylsulfanylpyrrolidine-2-carboxylate, followed byabout 1.5 equivalents of potassium carbonate. The reaction mixture isheated at 80° C. and stirred for about 72 hours. The compound ofstructure (16), wherein R² represents hydrogen, R⁴ represents SR⁷, andR⁷ represents (C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂R⁸, is then isolated usingstandard procedures. For example, the reaction mixture is washed withwater, the organic layer separated and dried over anhydrous sodiumsulfate, filtered, and concentrated under vacuum to provide crudecompound (16). Column chromatography can then be performed on silica gelwith a suitable eluent such as 10-50% ethyl acetate/hexane to providethe purified compound (16), wherein R² represents hydrogen, R⁴represents SR⁷, and R⁷ represents (C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂R⁸.

In Scheme V, Step E, following the procedures as described in Scheme I,Step E, compound (16) is deprotected under standard conditions wellknown in the art to provide the compound of Formula Ia, wherein R²represents hydrogen, R⁴ represents SR⁷, and R⁷ represents (C₁-C₄)alkylor (C₁-C₄)alkyl-CO₂R⁸. The material can then be concentrated andpurified by procedures well known in the art as described in Scheme I,Step E, to provide the purified compound of Formula Ia.

In Scheme V, Step F, following the procedures as described in Scheme I,Step F, the compound of Formula Ia is hydrolyzed to the compound ofFormula I, wherein wherein R² represents hydrogen, R¹ represents SR³,and R³ represents (C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂H, is hydrolyzed underconditions well known in the art. This material can then be concentratedand purified by techniques well known in the art as described in SchemeI, Step F to provide the purified compound of Formula I, wherein whereinR² represents hydrogen, R¹ represents SR³, and R³ represents(C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂H.

In Scheme V, Step G, following the procedures as described in Scheme I,Step G, compound (16)(as described above) is deprotected and hydrolyzedconcomitantly to provide the compound of Formula I, wherein R²represents hydrogen, R¹ represents SR³, and R³ represents (C₁-C₄)alkylor (C₁-C₄)alkyl-CO₂H. The compound of Formula I can then be concentratedand purified by techniques well known in the art to provide the purifiedcompound of Formula I, wherein R² represents hydrogen, R¹ representsSR³, and R³ represents (C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂H.

In Scheme V, Step H, the compound of Formula I can be esterified, underconditions well known in the art as described in Scheme I, Step H, toprovide the compound of Formula Ia, wherein R² represents hydrogen, R⁴represents SR⁷, and R⁷ represents (C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂R⁸.For example, the compound of Formula I is dissolved in a suitableorganic solvent such as ethanol, and treated with an excess of asuitable acid. Examples of suitable acids include gaseous hydrochloricacid, aqueous sulfuric acid, p-toluene sulfonic acid, and the like withgaseous hydrochloric acid being preferred. The reaction mixture isheated to reflux (78-85° C.) for about 15-25 hours. The reaction mixtureis concentrated under vacuum to provide the crude compound of FormulaIa, wherein R² represents hydrogen, R⁴ represents SR⁷, and R⁷ represents(C₁-C₄)alkyl or (C₁-C₄)alkyl-CO₂R⁸. This material can then be purifiedby techniques well known in the art, such as cation exchangechromatography eluting with methanol/water followed by 2N ammonia inethanol to provide the purified compound of Formula Ia.

Scheme VI provides compounds of Formula I, wherein R¹ representshydrogen or hydroxy and R² represents hydrogen.

In Scheme VI, Step I, the intermediate (17) is treated under standardreductive amination conditions with a compound of formula (3), whereinR² represents hydrogen and R⁴ represents hydrogen or hydroxy, to providethe compound of structure (18). For example, a solution of compound(17), dissolved in a suitable organic solvent such as THF is treatedwith 1.0 equivalents of a compound of formula (3), such as4-hydroxy-L-proline ethyl ester, followed by about 1.4 equivalents ofsodium triacetoxyborohydride and about 1.0 equivalent of acetic acid.The reaction mixture is stirred at room temperature for about 18 hours.The compound (18), wherein R² represents hydrogen and R⁴ representshydrogen or hydroxy, is then isolated using standard procedures. Forexample, the reaction mixture is partitioned between 3:1 CHCl₃/IPA andwater, the organic layer is separated and dried over anhydrous sodiumsulfate, filtered, and concentrated under vacuum to provide crudecompound (18), wherein R² represents hydrogen and R⁴ represents hydrogenor hydroxy. Column chromatography can then be performed on silica gelwith a suitable eluent such as 75% ethyl acetate/hexane to provide thepurified compound (18).

In Scheme VI, Step E, following the procedures as described in Scheme I,Step E, compound (18) is deprotected under standard conditions wellknown in the art to provide the compound of Formula Ia, wherein R²represents hydrogen and R⁴ represents hydrogen or hydroxy. The materialcan then be purified by techniques well known n the art as described inScheme I, Step E, to provide the purified compound of Formula Ia,wherein R² represents hydrogen and R⁴ represents hydrogen or hydroxy.

In Scheme VI, Step F, following the procedures as described in Scheme I,Step F, the compound of Formula Ia is hydrolyzed to the compound ofFormula I, wherein R² represents hydrogen and R¹ represents hydrogen orhydroxy, under conditions well known in the art. This material may thenbe concentrated and purified by techniques well known in the art asdescribed in Scheme I, Step F, to provide the purified compound ofFormula I, wherein R² represents hydrogen and R¹ represents hydrogen orhydroxy.

In Scheme VI, Step G, following the procedures as described in Scheme I,Step G, compound (18) is deprotected and hydrolyzed concomitantly toprovide the compound of Formula I, wherein R² represents hydrogen and R¹represents hydrogen or hydroxy. The compound of Formula I can then beconcentrated and purified by techniques well known in the art asdescribed in Scheme I, Step G, to provide the purified compound ofFormula I, wherein R² represents hydrogen and R¹ represents hydrogen orhydroxy.

In Scheme VI, Step H, following the procedures as described in Scheme I,Step H, the compound of Formula I can be esterified, under conditionswell known in the art as described in Scheme I, Step H, to provide thecompound of Formula Ia. For example, the compound of Formula I, whereinR² represents hydrogen and R¹ represents hydrogen or hydroxy. Thismaterial can then be concentrated and purified by techniques well knownin the art as described in Scheme I, Step H such as cation exchangechromatography eluting with methanol/water followed by 2N ammonia inethanol to provide the purified compound of Formula Ia, wherein R²represents hydrogen and R⁴ represents hydrogen or hydroxy.

Scheme VII provides procedures for the synthesis of compounds of FormulaII, wherein R⁹ is fluorine or hydroxy, and R¹⁰ is hydrogen.

In Scheme VII, Step A, the intermediate (19) is treated under standardreductive amination conditions with a compound of formula (20), toprovide the compound of structure (21). For example, a solution ofcompound (19) (ethyl-2-methoxycarbonyl-6-oxodecahydroisoquinoline3-carboxylate), dissolved in a suitable organic solvent such as THF istreated with 0.5 equivalents of a compound of formula (3), such as 3R,5S ethyl 5-hydroxypiperidine-3-carboxylate, followed by about 1.0equivalents of sodium triacetoxyborohydride and 1.0 equivalent of aceticacid. The reaction mixture is stirred at room temperature for about 72hours. The compound (21) is then isolated using standard procedures. Forexample, the reaction mixture is partitioned between 3:1 CHCl₃/IPA andwater, the organic layer is separated and dried over anhydrous sodiumsulfate, filtered, and concentrated under vacuum to provide crudecompound (21). Column chromatography can then be performed on silica gelwith a suitable eluent such as 5% MeOH/methylene chloride to provide thepurified compound (21).

In Scheme VII, Step E, the compound of structure (21) can be deprotecteddirectly under standard conditions to provide the compound of FormulaIIa, wherein for purposes of the present step, R⁹ represents hydroxy andR¹⁰ represents hydrogen. For example, when PG is a methoxycarbonylprotecting group, compound (21) is dissolved in a suitable organicsolvent such as dichloromethane under an atmosphere of nitrogen andtreated with trimethylsilyl iodide. The reation mixture is allowed towarm to room temperature and stirred for about 10-20 hours. The reactionis quenched by addition of saturated aqueous NaHCO₃. The aqueous layeris then extracted 2-6 times with dichloromethane. The organics are thencombined, washed with a 1N solution of sodium thiosulfate, dried overmagnesium sulfate, filtered, and concentrated in vacuo to provide thecompound of Formula IIa, wherein R⁹ represents hydroxy and R¹⁰represents hydrogen. The material can then be purified by chromatographyon silica gel with a suitable eluent such as methanol/dichoromethane, toprovide the purified compound of Formula IIa, wherein R⁹ representshydroxy and R¹⁰ represents hydrogen.

In Scheme VII, Step F, the compound of Formula IIa is hydrolyzed to thecompound of Formula II, wherein R⁹ represents hydroxy and R¹⁰ representshydrogen, under conditions well known in the art. For example, thecompound of Formula IIa is dissolved in a suitable organic solvent suchas methanol, and treated with an excess of a suitable base. Examples ofsuitable bases include aqueous lithium hydroxide, sodium hydroxide,potassium hydroxide, and the like, with lithium hydroxide beingpreferred. The reaction is stirred for about 10-20 hours. The reactionmixture is then neutralized to pH 6 with 1N HCl and concentrated undervacuum to provide the crude compound of Formula II, wherein R⁹represents hydroxy and R¹⁰ represents hydrogen. This material is thenpurified by techniques well known in the art, such as cation exchangechromatography eluting with THF/water followed by 10% pyridine in waterto provide the purified compound of Formula II, wherein R⁹ representshydroxy and R¹⁰ represents hydrogen.

In Scheme VII, Step G, compound (21) is deprotected and hydrolyzedconcomitantly to provide the compound of Formula II, wherein R⁹represents hydroxy and R¹⁰ represents hydrogen. For example, a solutionof compound (21) dissolved in 5N HCl is heated to reflux (90-95° C.) forabout 15-20 hours. The reaction mixture is then allowed to cool to roomtemperature and concentrated in vacuo to provide the compound of FormulaII, wherein R⁹ represents hydroxy and R¹⁰ represents hydrogen. Thecompound of Formula II can then be purified by techniques well known inthe art, such as cation exchange chromatography eluting withtetrahydrofuran/water followed by 10% pyridine/water to provide thepurified compound of Formula II, wherein R⁹ represents hydroxy and R¹⁰represents hydrogen.

In Scheme VII, Step H, the compound of Formula II can be esterified,under conditions well known in the art, to provide the compound ofFormula IIa, wherein R⁹ represents hydroxy and R¹⁰ represents hydrogen.For example, the compound of Formula II is dissolved in a suitableorganic solvent such as ethanol, and treated with an excess of asuitable acid. Examples of suitable acids include gaseous hydrochloricacid, aqueous sulfuric acid, p-toluene sulfonic acid, and the like withgaseous hydrochloric acid being preferred. The reaction mixture isheated to reflux (78-85° C.) for about 15-25 hours. The reaction mixtureis concentrated under vacuum to provide the crude compound of FormulaIIa. This material can then be purified by techniques well known in theart, such as cation exchange chromatography eluting with methanol/waterfollowed by 2N ammonia in ethanol to provide the purified compound ofFormula IIa, wherein R⁹ represents hydroxy and R¹⁰ represents hydrogen.

Alternatively, in Step B, Compound (21) from Step A above can beconverted, under standard fluorination conditions well known in the art,to provide compound (22), wherein R⁹ represents fluorine and R¹⁰represents hydrogen. For example, in Scheme VII, Step B, the compound ofstructure (21), is treated with diethylamino sulfur trifluoride to yieldthe intermediate of structure (22) wherein for purposes of the presentscheme, R⁹ represents fluorine and R¹⁰ represents hydrogen. For example,to a mixture of compound (21), cooled to about −78° C. in CH₂Cl₂, isadded dropwise diethylamino sulfur trifluoride. The reaction is allowedto warm to room temperature, stirred for about 48 hours, and quenched byaddition of MeOH. The compound of strucure (22) wherein for purposes ofthe present scheme, R⁹ represents fluorine and R¹⁰ represents hydrogen,is then isolated under standard conditions. For example, compound (22)is first concentrated under vacuum, then the residue partitioned between3:1 CHCl₃/IPA and aqueous NaHCO₃. The aqueous layer is then extractedwith 3:1 CHCl₃/IPA and the combined organics dried over MgSO₄, filtered,and concentrated under vacuum to provide the concentrated compound (22)wherein for purposes of the present scheme, R⁹ represents fluorine andR¹⁰ represents hydrogen. This material may then be purified bytechniques well known in the art such as chromatography on silica gelwith a suitable eluent, such as 25-50% EtOAc/hexane to provide thepurified compound of structure (22).

Compound (22) can then be deprotected and hydrolyzed under standardconditions well known in the art, as previously described herein forScheme VII, Steps E and F above, to provide the compounds of Formula IIaand Formula II, wherein R⁹ represents fluorine and R¹⁰ representshydrogen. Alternatively, the compound of structure (22) may bedeprotected and hydrolyzed concomitantly under standard conditions, aspreviously described herein for Scheme VII, Step G, to provide thecompound of Formula II wherein R⁹ represents fluorine and R¹⁰ representshydrogen. The compound of Formula II may then be esterified, again understandard conditions well known in the art as described previously forScheme VII, Step H, to provide the compound of Formula IIa, wherein R⁹represents fluorine and R¹⁰ represents hydrogen.

In order to obtain compounds of Formula II, wherein R⁹ representsfluorine or hydroxy and R¹⁰ represents hydrogen, and wherein the 3,5substituents of the piperidine moiety are trans in relation to eachother, the C-5 hydroxy group of structure (21) may be inverted via astandard Mitsunobu reaction, as shown in Scheme VII(a)

For example, In Scheme VII(a), Step C, when PG is a methoxycarbonylprotecting group, compound (21), dissolved in a suitable organic solventsuch as tetrahydrofuran, is cooled to 0° C. and charged with 4equivalents of triphenylphosphine followed by 4 equivalents of benzoicacid. The reaction mixture is allowed to warm to room temperature andstirred for about 48 hours. The material is then loaded onto an SCXcation exchange cartridge, and eluted with ethanol, followed by 2 Mammonia in ethanol. The material can then be purified by chromatographyon silica gel with a suitable eluent such as methanol/dichloromethane,to provide the purified compound of structure (21a).

In Scheme VII(a), Step G, the compound of structure (21a) may bedeprotected and hydrolyzed concomitantly under standard conditions, asdescribed in Scheme VII, Step G above, to provide the compound ofFormula II, wherein R⁹ represents hydroxy, R¹⁰ represents hydrogen, andwherein the C-3 and C-5 substituents of the piperidine moiety of FormulaII are trans in relation to each other.

Alternatively, in Scheme VII(a), Step D, the C-5 benzoyl ester group ofcompound (21a) is hydrolyzed to the C-5 hydroxy group as shown instructure (21b). Compound (21b) is then converted, under standardfluorination conditions, to the compound of structure (22), wherein R⁹is flourine, R¹⁰ is hydrogen, and the C-3 and C-5 substituents of thepiperidine moiety of structure (22) are trans in relation to each otherFor example, in Scheme VI(a), Step D, compound (21a) is dissolved in anappropriate solvent such as ethanol, to which concentrated sulfuric acid(approximately 3 equivalents) is added. The reaction is heated at 80° C.for a period of about 72 hours, then concentrated in vacuo. The residueis partitioned between 3:1 CHCl₃/IPA and aqueous sodium hydroxide. Theaqueous layer is then extracted with 3:1 CHCl₃/IPA and the combinedorganics dried over MgSO₄, filtered, and concentrated under vacuum toprovide compound (21b) wherein the C-3 and C-5 substituents of thepiperidine moiety are trans in relation to each other. This material maythen be purified by techniques well known in the art such aschromatography on silica gel with a suitable eluent, such as 30%methanol/methylene chloride to provide the purified compound ofstructure (21b).

Compound (21b) may then be converted to compound (22), wherein forpurposes of the present scheme R⁹ represents flurione, R¹⁰ representshydrogen, and wherein the C-3 and C-5 substituents of the piperidinemoiety are trans in relation to each other, under the same standardfluorination conditions as described in Scheme VII, Step B.

Compound (22) of the present scheme may then be deprotected andhydrolyzed under standard conditions well known in the art, aspreviously described herein for Scheme VII, Steps E and F above, toprovide the compounds oaf Formula II and IIa, wherein R⁹ representsflurione, R¹⁰ represents hydrogen, and wherein the C-3 and C-5substituents of the piperidine moiety are trans in relation to eachother. Alternatively, the compound of structure (22) may be deprotectedand hydrolyzed concomitantly under standard conditions, as previouslydescribed herein for Scheme VII, Step G, to provide the compound ofFormula II wherein R⁹ represents fluorine, R¹⁰ represents hydrogen, andand wherein the C-3 and C-5 substituents of the piperidine moiety aretrans in relation to each other. The compound of Formula II may then beesterified, again under standard conditions well known in the art asdescribed previously for Scheme VII, Step H, to provide the compounds ofFormula Ha, wherein R⁹ represents fluorine, R¹⁰ represents hydrogen, andand wherein the C-3 and C-5 substituents of the piperidine moiety aretrans in relation to each other.

Scheme VIII provides procedures for the synthesis of compounds ofFormula II, wherein R⁹ and R¹⁰ each independently represents fluorine,or R⁹ and R¹⁰, together, represent an oxo group.

In Scheme VII, Step C, treatment of compound (21) under standardoxidizing conditions provides the ketone intermediate of compound (23).For example, compound (21) can be added to a mixture of 1.3 equivalentsof oxalyl chloride and 2.5 equivalents of DMSO at −78° C., followed byaddition of approx. 5.0 equivalents of triethylamine, and subsequentwarming of the reaction to room temperature. The reaction mixture ispartitioned between water and an organic solvent such as methylenechloride, and the aqueous layer extracted 2-6 times with methylenechloride. The organic layers are combined, dried over anhydrous sodiumsulfate, filtered, and concentrated under vacuum to provide the ketonecompound of structure (23). Compound (23) can then be purified bychromatography on silica gel with a suitable eluent such as ethylacetate/hexanes or methanol/chloroform.

In Scheme VIII, Step E, compound (23) is deprotected under standardconditions well known in the art to provide the compound of Formula IIa,wherein R⁹ and R¹⁰ together represent an oxo group. For example, when PGis a methoxycarbonyl protecting group, compound (23) is dissolved in asuitable organic solvent such as dichloromethane under an atmosphere ofnitrogen and treated with trimethylsilyl iodide. The reation mixture isallowed to warm to room temperature and stirred for about 10-20 hours.The reaction is quenched by addition of saturated aqueous NaHCO₃. Theaqueous layer is then extracted 2-6 times with dichloromethane. Theorganics are then combined, washed with a 1N solution of sodiumthiosulfate, dried over magnesium sulfate, filtered, and concentrated invacuo to provide the compound of Formula IIa, wherein R⁹ and R¹⁰together represent an oxo group. This material can then be purified bychromatography on silica gel with a suitable eluent such asmethanol/dichoromethane, to provide the purified compound of FormulaIIa, wherein R⁹ and R¹⁰ together represent an oxo group.

In Scheme VIII, Step F, the compound of Formula H[a is hydrolyzed to thecompound of Formula II, wherein R⁹ and R¹⁰ together represent an oxogroup, under conditions well known in the art. For example, the compoundof Formula IIa is dissolved in a suitable organic solvent such asmethanol, and treated with an excess of a suitable base. Examples ofsuitable bases include aqueous lithium hydroxide, sodium hydroxide,potassium hydroxide, and the like, with lithium hydroxide beingpreferred. The reaction is stirred for about 10-20 hours. The reactionmixture is then neutralized to pH 6 with 1N HCl and concentrated undervacuum to provide the crude compound of Formula II, wherein R⁹ and R¹⁰together represent an oxo group. This material can then be purified bytechniques well known in the art, such as cation exchange chromatographyeluting with tetrahydrofuran/water followed by 10% pyridine/water toprovide the purified compound of Formula II, wherein R⁹ and R¹⁰ togetherrepresent an oxo group.

In Scheme II, Step G, compound (23) may be deprotected and hydrolyzedconcomitantly to provide the compound of Formula II, wherein R⁹ and R¹⁰together represent an oxo group. For example, a solution of compound(23) dissolved in 5N HCl is heated to reflux (90-95° C.) for about 15-20hours. The reaction mixture is then allowed to cool to room temperatureand concentrated in vacuo to provide the compound of Formula II, whereinR⁹ and R¹⁰ together represent an oxo group. The compound of Formula IIcan then be purified by techniques well known in the art, such as cationexchange chromatography eluting with tetrahydrofuran/water followed by10% pyridine/water to provide the purified compound of Formula II,wherein R⁹ and R¹⁰ together represent an oxo group.

In Scheme VIII, Step H, the compound of Formula II, wherein R⁹ and R¹⁰together represent an oxo group, can be esterified, under conditionswell known in the art, to provide the compound of Formula IIa, R⁹ andR¹⁰ together represent an oxo group. For example, the compound ofFormula II is dissolved in a suitable organic solvent such as ethanol,and treated with an excess of a suitable acid. Examples of suitableacids include gaseous hydrochloric acid, aqueous sulfuric acid,p-toluene sulfonic acid, and the like with gaseous hydrochloric acidbeing preferred. The reaction mixture is heated to reflux (78-85° C.)for about 15-25 hours. The reaction mixture is concentrated under vacuumto provide the crude compound of Formula IIa, wherein R⁹ and R¹⁰together represent an oxo group. This material can then be purified bytechniques well known in the art, such as cation exchange chromatographyeluting with methanol/water followed by 2N ammonia in ethanol to providethe purified compound of Formula IIa, wherein R⁹ and R¹⁰ togetherrepresent an oxo group.

Alternatively, in Scheme VIII, Step D the compound of structure (23) isconverted to the intermediate of structure (24), wherein for purposes ofthe present step, R⁹ and R¹⁰ each independently represent fluorine.Procedures for synthesizing compounds of structure (24), wherein R⁹ andR¹⁰ both represent fluorine, are provided herein essentially asdescribed in Scheme I, Step D supra.

Compound (24) can then be deprotected and hydrolyzed under standardconditions well known in the art, as previously described herein forScheme VIII, Steps E and F above, to provide the compounds of FormulaIIa and Formula II, wherein R⁹ and R¹⁰ each independently representfluorine. Alternatively, the compound of structure (24) may bedeprotected and hydrolyzed concomitantly under standard conditions, aspreviously described herein for Scheme VIII, Step G, to provide thecompound of Formula II wherein R⁹ and R¹⁰ each independently representfluorine. The compound of Formula II may then be esterified, again understandard conditions well known in the art as described previously forScheme VIII, Step H, to provide the compound of Formula IIa, wherein R⁹and R¹⁰ each independently represent fluorine.

Scheme IX provides procedures for the synthesis of compounds of FormulaII, wherein R⁹ represents tetrazole or a group of the formula:

wherein X represents (C₁-C₄)alkyl or phenyl, and R¹⁰ representshydrogen.

In Scheme IX, Step C, compound (21) is treated with a compound ofstructure (25), wherein X represents hydrogen, (C₁-C₄)alkyl, or phenyl,in the presence of triphenylphosphine and DEAD to give the compound ofstructure (26), wherein R⁹ is tetrazole or a group of the structure (a):

(wherein X for the purposes of Structure (a) represents (C₁-C₄)alkyl orphenyl) and R¹⁰ represents hydrogen. For example, a solution compound(21) about 1-1.4 equivalents of compound (25) (wherein X representshydrogen, (C₁-C₄)alkyl, or phenyl) and about 1-1.4 equivalents oftriphenylphosphine in tetrahydrofuran is cooled to 0° C. Diethylazodicarboxylate (1-1.4 equivalents) is added and the reaction isallowed to warm to room temperature then stirred for about 72 hours. Thereaction may then be purified by chromatography on SCX resin with asuitable eluent such as 2 N ammonia in ethanol, to provide compound(26), wherein R⁹ represents tetrazole or group of Structure (a) asprovided herein above. Compound (26) can then be further purified bychromatography on silica gel with a suitable eluent such as ethylacetate/hexanes.

In Scheme IX, Step E, compound (26), wherein R⁹ represents tetrazole orgroup of Structure (a) (as provided herein in Scheme 1×, Step C above),is deprotected under standard conditions well known in the art toprovide the compound of Formula IIa, wherein R⁹ represents tetrazole orgroup of Structure (a) (as provided herein in Scheme IX, Step C above).For example, when PG is a methoxycarbonyl protecting group, compound(26) is dissolved in a suitable organic solvent such as dichloromethaneunder an atmosphere of nitrogen and treated with trimethylsilyl iodide.The reation mixture is allowed to warm to room temperature and stirredfor about 10-20 hours. The reaction is quenched by addition of saturatedaqueous NaHCO₃. The aqueous layer is then extracted 2-6 times withdichloromethane. The organics are then combined, washed with a 1Nsolution of sodium thiosulfate, dried over magnesium sulfate, filtered,and concentrated in vacuo to provide the compound of Formula IIa,wherein R⁹ represents tetrazole or group of Structure (a) (as providedherein in Scheme IX, Step C above). The material can then be purified bychromatography on silica gel with a suitable eluent such asmethanol/dichoromethane, to provide the purified compound of FormulaIIa, wherein R⁹ represents tetrazole or group of Structure (a) (asprovided herein in Scheme IX, Step C above).

In Scheme IX, Step F, the compound of Formula IIa from Step E above, ishydrolyzed under conditions well known in the art to the compound ofFormula II, wherein R⁹ represents tetrazole or group of Structure (a)(as provided herein in Scheme IX, Step C above). For example, thecompound of Formula i]a, from Scheme IX, Step. E, is dissolved in asuitable organic solvent such as methanol, and treated with an excess ofa suitable base. Examples of suitable bases include aqueous lithiumhydroxide, sodium hydroxide, potassium hydroxide, and the like, withlithium hydroxide being preferred. The reaction is stirred for about10-20 hours. The reaction mixture is then neutralized to pH 6 with 1NHCl and concentrated under vacuum to provide the crude compound ofFormula II, wherein R⁹ represents tetrazole or group of Structure (a)(as provided herein in Scheme IX, Step C above). This material may thenbe purified by techniques well known in the art, such as cation exchangechromatography eluting with tetrahydrofuran/water followed by 10%pyridine/water to provide the purified compound of Formula II, whereinR⁹ represents tetrazole or group of Structure (a) (as provided herein inScheme IX, Step C above).

In Scheme IX, Step G, compound (26) is deprotected and hydrolyzedconcomitantly to provide the compound of Formula II, wherein R⁹represents tetrazole or group of Structure (a) (as provided herein inScheme IX, Step C above). For example, a solution of compound (26)dissolved in 5N HCl is heated to reflux (90-95° C.) for about 15-20hours. The reaction mixture is then allowed to cool to room temperatureand concentrated in vacuo to provide the compound of Formula II, whereinR⁹ represents tetrazole or group of Structure (a) (as provided herein inScheme IX, Step C above). The compound of Formula II can then bepurified by techniques well known in the art, such as cation exchangechromatography eluting with tetrahydrofuran/water followed by 10%pyridine/water to provide the purified compound of Formula II, whereinR⁹ represents tetrazole or group of Structure (a) (as provided herein inScheme IX, Step C above).

In Scheme IX, Step H, the compound of Formula II can be esterified,under conditions well known in the art, to provide the compound ofFormula Ia, wherein R⁹ represents tetrazole or group of Structure (a)(as provided herein in Scheme IX, Step C above). For example, thecompound of Formula II, wherein R⁹ represents tetrazole or group ofStructure (a) (as provided herein in Scheme IX, Step C above) isdissolved in a suitable organic solvent such as ethanol, and treatedwith an excess of a suitable acid. Examples of suitable acids includegaseous hydrochloric acid, aqueous sulfuric acid, p-toluene sulfonicacid, and the like with gaseous hydrochloric acid being preferred. Thereaction mixture is heated to reflux (78-85° C.) for about 15-25 hours.The reaction mixture is concentrated under vacuum to provide the crudecompound of Formula IIa, wherein R⁹ represents tetrazole or group ofStructure (a) (as provided herein in Scheme IX, Step C above). Thismaterial can then be purified by techniques well known in the art, suchas cation exchange chromatography eluting with methanol/water followedby 2N ammonia in ethanol to provide the purified compound of FormulaIIa, where R⁹ represents tetrazole or group of Structure (a) (asprovided herein in Scheme IX, Step C above).

The compounds of Formula I may be synthesized by one of ordinary skillin the art from intermediates previously disclosed in the art. Forexample, synthesis ofethyl-6-hydroxymethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylateis provided in U.S. Pat. No. 5,356,902, issued Oct. 18, 1994 and U.S.Pat. No. 5,670,516, issued Sep. 23, 1997; synthesis ofethyl-6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylateis provided in U.S. Pat. No. 5,670,516, issued Sep. 23, 1997; andsynthesis ofethyl-6-formyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate isprovided in U.S. Pat. No. 5,356,902, issued Oct. 18, 1994 and U.S. Pat.No. 5,670,516, issued Sep. 23, 1997. These intermediates, in turn, maybe synthesized from the common intermediateethyl-2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylate, thesynthesis of which is provided in U.S. Pat. No. 4,902,695, U.S. Pat. No.5,356,902, U.S. Pat. No. 5,446,051, and U.S. Pat. No. 5,670,516, thecontents, all of which, are herein incorporated by reference. Likewise,the compounds of Formula II may also be synthesized from the same commonintermediate,ethyl-2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylate.

A route for the synthesis of theethyl-2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylateintermediate, useful for the synthesis of the compounds of the presentinvention, is shown in Scheme X below. This intermediate may besynthesized from a2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylic acid, thesynthesis of which is described in U.S. Pat. No. 4,902,695, No.5,446,051, and No. 5,356,902 (the contents of which are all hereinincorporated by reference)

In Scheme X, Step A, the compound of structure (i) is esterified byreaction with a compound of formula Et-Br (where Et represents an ethylgroup) to provide the intermediate of compound (i-b). For example2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylic acid isdissolved in acetonitrile and treated with triethylamine andbromoethane. The reaction is heated at 50° C. for about 3 hours, cooledand partitioned between 50:50 ethyl acetate/heptane and 1N HCl. Theorganic phase is isolated and washed 3 times with water, saturatedsodium bicarbonate, brine, dried over anhydrous sodium sulfate,filtered, and concentrated under vacuum to provideethyl-2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylate, thecompound of structure (i-b). This crude material may then be purifiedunder standard conditions well known in the art. For example, the crudematerial is dissolved in 10% ethyl acetate/heptane and applied to a plugof silica gel (10 g in 10% ethyl acetate/heptane). The plug is elutedwith, 10% ethyl acetate/heptane, 15% ethyl acetate/heptane, and 25%ethyl acetate/heptane. The eluents are combined and concentrated undervacuum to provide the purified compound of structure (i-b).

Routes for the synthesis of theethyl-6-hydroxymethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylateintermediate, useful for the synthesis of the compounds of Formula I,are shown in Schemes XIa and XIb below.

In Scheme XI(a), Step A, compound (i) is treated withmethyltriphenylphosphonium bromide to provide the6-methylidine-decahydroisoquinoline-3-carboxylic acid of compound (i-a).For example, a slurry of 1 equivalent of2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylic acid (Pg ismethoxycarbonyl) and about 1.4 equivalents of methyltriphenylphosphoniumbromide in THF and DMP is stirred mechanically under an atmosphere ofnitrogen and cooled to −10° C. Potassium tert-butoxide solution (2.4equiv in THF) is added dropwise over a 10 minute period. The slurry isallowed to warm to room temperature and stirred thus for about 2.5 hours(complete by TLC at this time). The reaction is partitioned betweenwater and EtOAc and the layers are separated. The organic phase isextracted 2 times with water and the aqueous portions are combined andwashed 2-6 times with dichloromethane. The aqueous solution is madeacidic by addition of 6 M HCl solution and extracted 2-6 times withdichloromethane. These last three organic extracts are combined, driedwith sodium sulfate and concentrated under reduced pressure to providethe compound of structure (i-a).

In Scheme XI(a), Step B, the intermediate6-methylidine-2-methoxycarbonyl decahydroisoquinoline-3-carboxylic acid(compound (i-a)) is esterified by reaction with a compound of formulaEt-Br (where Et represents an ethyl group) to provide the6-methylidine-decahydroisoquinoline-3-carboxylate intermediate ofcompound (ii-a). For example6-methylidine-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylic acidis dissolved in acetonitrile and treated with triethylamine andbromoethane. The reaction is heated at 50° C. for about 3 hours, cooledand partitioned between 50:50 ethyl acetate/heptane and 1N HCL. Theorganic phase is isolated and washed 3 times with water, saturatedsodium bicarbonate, brine, dried over anhydrous sodium sulfate,filtered, and concentrated under vacuum to provide the compound ofstructure (ii-a). This crude material is dissolved in 10% ethylacetate/heptane and applied to a plug of silica gel (10 g in 10% ethylacetate/heptane). The plug is eluted with, 10% ethyl acetate/heptane,15% ethyl acetate/heptane, and 25% ethyl acetate/heptane. The eluentsare combined and concentrated under vacuum to provide the purifiedcompound of structure (ii-a).

In Scheme XI(a), Step C, the6-methylidine-decahydroisoquinoline-3-carboxylate intermediate (compound(ii-a)) is subjected to hydroboration, followed by oxidation to providethe 6-hydroxymethyl-decahydroisoquinoline-3-carboxylate intermediate ofcompound (A). For example,ethyl-6-methylidine-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylateis dissolved in THF and cooled to about −15° C. under an atmosphere ofnitrogen with stirring. A 1M solution of BH₃.THF is added dropwise over5-7 minutes and the reaction mixture is stirred for about 2 hours at −10to −12° C. The reaction is then slowly treated with a suitable base,such as lithium or sodium hydroxide, and then treated slowly with 30%H₂O₂ over 15 minutes. The reaction mixture is allowed to warm to roomtemperature and then partitioned between ethyl acetate and 50% saturatedsodium chloride solution. The aqueous layer is extracted with ethylacetate and the combined organics are washed with sodium bisulfitesolution, brine, dried over anhydrous sodium sulfate, filtered, andconcentrated under vacuum to provide the intermediate of compound (A).

Alternatively, the6-hydroxymethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylateintermediate (compound (A)) may be made according to the synthetic routedescribed in Scheme XI(b). In Scheme XI(b), Step A,2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylic acid (Pg ismethoxycarbonyl) is esterified by reaction with a compound of formulaEt-Br (where Et represents an ethyl group) to provide the6-oxo-decahydroisoquinoline-3-carboxylate intermediate of compound(i-b). For example2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylic acid isdissolved in acetonitrile and treated with triethylamine andbromoethane. The reaction is heated at 50° C. for about 3 hours, cooledand partitioned between 50:50 ethyl acetate/heptane and 1N HCl. Theorganic phase is isolated and washed 3 times with water, saturatedsodium bicarbonate, brine, dried over anhydrous sodium sulfate,filtered, and concentrated under vacuum to provide the compound ofstructure (i-b). This crude material is dissolved in 10% ethylacetate/heptane and applied to a plug of silica gel (10 g in 10% ethylacetate/heptane). The plug is eluted with 10% ethyl acetate/heptane, 15%ethyl acetate/heptane, and 25% ethyl acetate/heptane. The eluents arecombined and concentrated under vacuum to provide the purified compoundof structure (i-b).

In Scheme XI(b), Step B, the 6-oxodecahydroisoquinoline-3-carboxylateintermediate of compound (i-b) is treated withmethyltriphenylphosphonium bromide to provide the6-methylidine-decahydroisoquinoline-3-carboxylate of compound (ii-b).For example a slurry of 1 equivalent ofethyl-2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylate(compound (i-b)) and about 1.4 equivalents of methyltriphenylphosphoniumbromide in THF and DMP is stirred mechanically under an atmosphere ofnitrogen and cooled to −10° C. Potassium tert-butoxide solution (2.4equiv in THF) is added dropwise over a 10 minute period. The slurry isallowed to warm to room temperature and stirred thus for 2.5 hours(complete by TLC at this time). The reaction is partitioned betweenwater and EtOAc and the layers are separated. The organic phase isextracted 2 times with water and the aqueous portions are combined andwashed 2-6 times with dichloromethane. The aqueous solution is madeacidic by addition of 6 M HCl solution and extracted 2-6 times withdichloromethane. These last three organic extracts are combined, driedwith sodium sulfate and concentrated under reduced pressure to providethe compound of structure (ii-b).

In Scheme XI(b), Step C, following the procedures as described in SchemeII(a), Step C above, the6-methylidine-decahydroisoquinoline-3-carboxylate intermediate (compound(ii-b)) is subjected to hydroboration, followed by oxidation to providethe ethyl6-hydroxymethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylateintermediate of compound (A).

The following preparations and examples further illustrate the inventionand represent typical synthesis of the compounds of Formula I andFormula II as described generally above. The reagents and startingmaterials are readily available to one of ordinary skill in the art. Asused herein, the following terms have the meanings indicated: “i.v.”refers to intravenously; “p.o.” refers to orally; “i.p.” refers tointraperitoneally; “eq” or “equiv.” refers to equivalents; “g” refers tograms; “mg” refers to milligrams; “V” refers to liters; “mL” refers tomilliliters; “μL” refers to microliters; “mol” refers to moles; “mmol”refers to millimoles; “psi” refers to pounds per square inch; “mm Hg”refers to millimeters of mercury; “min” refers to minutes; “h” or “hr”refers to hours; “° C.” refers to degrees Celsius; “TLC” refers to thinlayer chromatography; “HPLC” refers to high performance liquidchromatography; “R_(f)” refers to retention factor; “R_(t)” refers toretention time; “δ” refers to part per million down-field fromtetramethylsilane; “THF” refers to tetrahydrofuran; “DMF” refers toN,N-dimethylformamide; “DMSO” refers to dimethyl sulfoxide; “aq” refersto aqueous; “EtOAc” refers to ethyl acetate; “IPA” refers to isopropylalcohol; “iPrOAc” refers to isopropyl acetate; “MeOH” refers tomethanol; “MTBE” refers to tert-butyl methyl ether; “PPh₃” refers totriphenylphosphine; “DEAD” refers to diethyl azodicarboxylate; “RT”refers to room temperature; “Pd—C” refers to palladium over carbon;NaBH(Oac)₃ refers to sodium triacetoxyborohydride; “Bn” refers tobenzyl; “BnNH₂” refers to benzyl amine; H₂ refers to hydrogen; “K_(i)”refers to the dissociation constant of an enzyme-antagonist complex andserves as an index of ligand binding; and “ID₅₀” and “ID₁₀₀” refer todoses of an administered therapeutic agent which produce, respectively,a 50% and 100% reduction in a physiological response.

EXAMPLE 1 Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-4,4difluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((4-Methylphenyl)sulfonyloxy)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 15.0 g (50.1 mmol) of 3S, 4aR, 6S, 8aR ethyl6-hydroxymethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) cooled to 0° C. in CH₂Cl₂ (100mL), was added triethylamine (20.9 mL, 150.3 mmol) followed byp-toluenesulfonyl chloride (19.1 g, 100.2 mmol) dissolved in CH₂Cl₂ (100mL). The reaction was warmed to room temperature and stirred 16 h, thenpartitioned between CH₂Cl₂ and 10% aqueous NaHSO₄. The aqueous layer wasextracted with CH₂Cl₂ and the combined organics were dried over MgSO₄,filtered, and concentrated in vacuo. Column chromatography (Stepwisegradient: 10-50% EtOAc/hexane) provided 20.1 g (89%) of the desiredintermediate title compound as a colorless oil:

MS(m/e): 451.5 (M⁺)

Calculated for C₂₂H₃₁NO₇S.0.25H₂O: Theory: C, 57.69; H, 6.93; N, 3.06.Found: C, 57.76; H, 6.93; N, 3.35

¹³C NMR (DMSO-d₆): δ 171.4, 144.8, 132.4, 130.1, 127.6, 74.6, 60.4,53.1, 52.4, 44.1, 34.6, 31.8, 31.0, 29.8, 28.8, 24.9, 23.3, 21.0, 14.0ppm

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of trans-4-hydroxy-L-proline ethyl ester-hydrochloride (6.5 g,33.1 mmol), the compound of Step A above (10.0 g, 22.0 mmol), andpotassium carbonate (4.6 g, 33.1 mmol) were heated at reflux inacetonitrile (22 mL) for 60 h. The reaction mixture was cooled to roomtemperature, and partitioned between CH₂Cl₂ and H₂O. The aqueous layerwas extracted two times with CH₂Cl₂ and the combined organics were driedover MgSO₄, filtered, and concentrated in vacuo. Column chromatography(50% EtOAc/hexane followed by 5% MeOH/CH₂Cl₂) gave 9.2 g (95%) of thedesired intermediate title compound as a colorless oil:

MS(m/e): 441.3 (M⁺)

Calculated for C₂₂H₃₆N₂O₇S: Theory: C, 59.98; H, 8.24; N, 6.36. Found:C, 60.17; H, 8.23; N, 6.42

C. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)₄-oxopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of DMSO (2.3 mL, 32.5 mmol) cooled to −78° C. in CH₂Cl₂(25 mL) was added, dropwise, oxalyl chloride (1.4 mL, 16.3 mmol). Thereaction mixture was stirred for 5 min, then the compound of Step Babove (6.0 g, 13.6 mmol) dissolved in 20 mL of CH₂Cl₂ was added. Uponstirring for 0.75 h at −78° C., triethylamine (9.5 mL, 32.5 mmol) wasadded. The reaction was warmed to room temperature over approximately 2hours, and quenched by the addition of 10% aqueous NaHSO₄. The aqueouslayer was extracted with CH₂Cl₂ and the combined organics were driedover MgSO₄, filtered, and concentrated in vacuo. Column chromatography(Stepwise gradient: 25-50% EtOAc/hexane) provided 4.6 g (78%) of thedesired intermediate title compound as a colorless oil:

MS(m/e): 439.1 (M⁺)

D. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-4,4-difluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a mixture of the compound of Step C above (4.62 g, 10.5 mmol) cooledto −78° C. in CH₂Cl₂ (50 mL) was added, dropwise, diethylaminosulfurtrifluoride (3.5 mL, 26.3 mmol). The reaction was allowed to warm toroom temperature, stirred an additional 48 h, then quenched by theaddition of MeOH. After concentrating in vacuo, the residue waspartitioned between CH₂Cl₂ and saturated aqueous NaHCO₃. The aqueouslayer was extracted with CH₂Cl₂ and the combined organics were driedover MgSO₄, filtered, and concentrated in vacuo. Column chromatography(Stepwise gradient: 25-50% EtOAc/hexane) provided 3.3 g (68%) of thedesired intermediate title compound as a colorless oil:

MS(m/e): 461.2 (M⁺)

Calculated for C₂₂H₃F₂N₂O₆: Theory: C, 57.38; H, 7.44; N, 6.08. Found:C, 57.28; H, 7.52; N, 6.13

E. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-4,4-difluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of the compound of Step D above (3.3 g, 7.10 mmol) dissolvedin CH₂Cl₂ (40 mL) was cooled to 0° C. and charged withiodotrimethylsilane (3.0 mL, 21.3 mmol). The reaction was allowed towarm to room temperature, stirred an additional 4 h, then quenched bythe addition of saturated aqueous NaHCO₃ (50 mL). The aqueous layer wasextracted with CH₂Cl₂ and the combined organics washed with 1 N NaS₂O₃,dried over MgSO₄, filtered, and concentrated in vacuo. The material waschromatographed (2% MeOH/CH₂Cl₂), dissolved in 20 mL of Et₂O, and to itwas added 50 mL of 2 M HCl/Et₂O. The solvent was removed in vacuo,providing 2.6 g (76%) of the final title compound as a white solid:

MS(m/e): 403.4 (M⁺)

Calculated for C₂₀H₃₂.Cl₂F₂N₂O₄: Theory: C, 50.53; H, 7.21; N, 5.89.Found: C, 50.90; H, 7.41; N, 5.84

¹³C NMR D₂O): δ 170.3, 167.7, 125.1 (t, J_(C-F)=249.1 Hz), 65.9, 65.0,64.1, 63.4, 60.1 (t, J_(C-F)=33.9 Hz), 57.6, 52.8, 42.9, 37.2 (t,J_(C-F)=26.4 Hz), 34.5, 31.7, 31.3, 30.5, 28.4, 26.9, 24.3, 13.6 ppm

EXAMPLE 2 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-4,4-difluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-4,4-difluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(3.3 g, 7.10 mmol), the compound from Step D of Example 1 above,dissolved in 5 N aqueous HCl (15 mL), was heated at 90° C. for 18 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam was dissolved in H₂O (75 mL) and stirredin the presence of Dowex 50×8 (100-200) ion-exchange resin (10 g) for 2h. The resin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O,then stirred in the presence of 10% pyridine/H₂O for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.6 g, 97%) as awhite foam:

MS(m/e): 347.2 (M⁺)

Calculated for C₁₆H₂₄F₂N₂O₄.0.1H₂O: Theory: C, 55.19; H, 7.01; N, 8.05.Found: C, 54.81; H, 6.82; N, 8.13

¹³C NMR (D₂O): δ 175.1, 171.1, 125.6 (t, J_(C-F)=249.4 Hz), 67.9, 63.0,59.3 (t, J_(C-F)=34.0 Hz), 54.5, 42.5, 37.5 (t, J_(C-F)=24.9 Hz), 34.3,32.7, 32.4, 30.6, 28.2, 27.0, 24.3 ppm

EXAMPLE 3 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)₄-fluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)₄-fluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 1.0 g (2.76 mmol) of 3S, 4aR, 6S, 8aR ethyl6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) dissolved in CH₃CN (2.5 mL) wasadded K₂CO₃ (0.57 g, 4.14 mmol), followed by trans-4-fluoro-L-prolineethyl ester (0.67 g, 4.14 mmol) (Demange, L.; Ménez, A.; Dugave, C.Tetrahedron Lett. 1998, 39, 1169-1172.). The reaction mixture was heatedat 80° C. for 72 h, then cooled to room temperature and loaded onto a 10g SCX Mega Bond Elut SPE cartridge (Varian Sample Preparation Products).The resin was washed sequentially with CH₂Cl₂ (50 mL) followed by MeOH(50 mL), then 2 M NH₃/MeOH (50 mL). Following concentration in vacuo,the resulting residue was chromatographed (50% EtOAc/hexane) to provide0.64 g (52%) of the desired intermediate title compound:

MS(m/e): 443.2 (M⁺)

Calculated for C₂₂H₃₅FN₂O₆: Theory: C, 59.71; H, 7.97; N, 6.33. Found:C, 59.79; H, 7.71; N, 6.37

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-fluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl 6-(((2S)-2-(ethoxycarbonyl)-(4R)₄fluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.40 g, 0.90 mmol), the compound of Step A above, dissolved in 5 Naqueous HCl (15 mL), was heated at 90° C. for 18 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O for 2 h. After filtration, the resinwas washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.25 g, 84%) as a white foam:

MS(m/e): 329.2 (M⁺)

Calculated for C₁₆H₂₄F₂N₂O₄.0.7H₂O: Theory: C, 56.36; H, 7.80; N, 8.22.Found: C, 56.38; H, 7.99; N, 8.00

¹³C NMR (D₂O): δ 175.6, 173.0, 94.7 (d, J_(C-F)=175.5 Hz), 70.0, 64.5,61.6 (d, J_(C-F)=24.3 Hz), 54.9, 42.9, 37.5 (d, J_(C-F)=21.2 Hz), 35.0,32.9, 32.7, 31.1, 28.7, 27.5, 24.7 ppm

EXAMPLE 4 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)₄-chloropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)₄-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of cis-4-hydroxy-L-proline (2.0 g, 15.3 mmol) cooled to 0° C.in 20 mL of EtOH was saturated with gaseous HCl. The reaction was warmedto room temperature and stirred 12 h, then concentrated in vacuo. Anexcess solution of 2 M NH3/MeOH was added, the solution was stirred for0.25 h, then allowed to stand for an additional 0.25 h. The residualsalt was removed via vacuum filtration, and the filtrate wasconcentrated in vacuo to provide 2.3 g (98%) of cis-hydroxy-L-prolineethyl ester, which was used without further purification.

To a solution of 3.6 g (10.0 mmol) of 3S, 4aR, 6S, 8aR ethyl6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) dissolved in CH₃CN (10 mL) wasadded K₂CO₃ (2.1 g, 15.0 mmol), followed by cis-hydroxy-L-proline ethylester (2.3 g, 15.0 mmol). The reaction mixture was heated at 80° C. for48 h, then cooled to room temperature and partitioned between CH₂Cl₂ andH₂O. The aqueous layer was extracted with CH₂Cl₂, and the combinedorganics were dried (MgSO₄) and concentrated in vacuo. The resultingresidue was chromatographed (50% EtOAc/hexane followed by 10%MeOH/CH₂Cl₂) to provide 3.83 g (87%) of the desired intermediate titlecompound.

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-Ethoxycarbonyl)-(4R)₄chloropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of triphenylphosphine (3.6 g, 13.6 mmol) and CCl₄ (1.3 mL,13.6 mmol) dissolved in CH₂Cl₂ (5 mL) was stirred at room temperaturefor 0.25 h. A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step A above, dissolved in CH₂Cl₂ (10 mL) was added, andthe reaction was stirred at room temperature for 20 h. The reaction waspartitioned between CH₂Cl₂ and 10% aqueous NaHSO₄, the aqueous layer wasextracted with CH₂Cl₂, and the combined organics were dried (MgSO₄) andconcentrated in vacuo. The resulting residue was chromatographed (50%EtOAc/hexane) to provide 0.63 g (30%) of the desired intermediate titlecompound:

MS(m/e): 459.5 (M⁺)

Calculated for C₂₂H₃₅ClN₂O₆: Theory: C, 57.57; H, 7.69; N, 6.10. Found:C, 57.47; H, 7.64; N, 6.02

C. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)₄-chloropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)₄-chloropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.63 g, 1.37 mmol), the compound of Step B above, cooled to 0° C. in 5mL of CH₂Cl₂, was charged with iodotrimethylsilane (0.59 mL, 4.12 mmol).The reaction was warmed to room temperature, stirred for 3 h, andquenched by the addition of saturated aqueous NaHCO₃ (50 mL). Theaqueous layer was extracted (CH₂Cl₂), and the combined organic layerswere washed sequentially with saturated aqueous NaHCO₃, 1N aqueousNa₂S₂O₃, then dried (MgSO₄) and concentrated in vacuo. The resultingresidue was chromatographed (50% MeOH/CH₂Cl₂) to provide 0.54 g (98%) ofthe amine intermediate, which was dissolved in 5 N aqueous HCl (15 mL)and heated at 50-70° C. for a total of 30 h. The reaction mixture wascooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O for 2 h. After filtration, the resinwas washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.35 g, 75%) as a white foam:

MS(m/e): 345.1 (M⁺)

Calculated for C₁₆H₂₅ClN₂O₄: Theory: C, 55.73; H, 7.31; N, 8.12. Found:C, 55.38; H, 7.64; N, 8.06

¹³C NMR (D₂O): δ 175.6, 173.0, 70.1, 65.1, 63.7, 56.3, 55.0, 43.0, 40.3,35.1, 33.1, 32.7, 31.1, 28.7, 27.5, 24.8 ppm

EXAMPLE 5 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-fluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)₄-fluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 1.0 g (2.76 mmol) of 3S, 4aR, 6S, 8aR ethyl6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) dissolved in CH₃CN (2.8 mL) wasadded K₂CO₃ (0.57 g, 4.14 mmol), followed by cis-4-fluoro-L-prolineethyl ester (0.57 g, 4.14 mmol) (prepared by one of ordinary skill inthe art following the procedures disclosed in Tetrahedron Lett., 39,1169-1172 (1998)). The reaction mixture was heated at 80° C. for 120 h,cooled to room temperature, then partitioned between CH₂Cl₂ and H₂O. Theaqueous layer was extracted with CH₂Cl₂, and the combined organics weredried (MgSO₄), and concentrated. The residue was loaded onto a 10 g SCXcartridge (Varian). The resin was washed sequentially with CH₂Cl₂ (50mL) followed by MeOH (50 mL), then 2 M NH3/MeOH (50 mL). Followingconcentration in vacuo, the resulting residue was chromatographed (50%EtOAc/hexane) to provide 0.75 g (61%) of the desired intermediate titlecompound:

MS(m/e): 443.2 (M⁺)

Calculated for C₂₂H₃₅FN₂O₆: Theory: C, 59.71; H, 7.97; N, 6.33. Found:C, 59.65; H, 8.06; N, 6.43

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-fluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid.

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)₄-fluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.30 g, 0.68 mmol), the compound of Step A above, dissolved in 5 Naqueous HCl (10 mL), was heated at 90° C. for 60 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.21 g, 94%) as a white foam:

MS(m/e): 329.2 (M⁺)

Calculated for C₁₆H₂₄F₂N₂O₄.1.0H₂O: Theory: C, 55.48; H, 7.86; N, 8.09.Found: C, 55.32; H, 7.68; N, 7.88

¹³C NMR (D₂O): δ 175.6, 174.0, 92.6 (d, J_(C-F)=175.1 Hz), 68.7, 62.1,61.9 (d, J_(C-F)=34.3 Hz), 55.0, 43.0, 36.6 (d, J_(C-F)=21.4 Hz), 35.1,32.9, 32.7, 31.1, 28.9, 27.5, 24.9 ppm

EXAMPLE 6 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)₄-bromopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Methoxycarbonyl)-(4S)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a mixture of acetyl chloride (2.3 mL, 32.0 mmol) cooled to 0° C. in40 mL of MeOH was added cis-4-hydroxy-L-proline (3.0 g, 22.9 mmol). Thereaction was heated at 50° C., stirred for 5 h, then cooled and dilutedwith Et₂O. The solid was collected by vacuum filtration and dried toprovide 3.4 g (81%) of cis-hydroxy-L-proline methyl ester hydrochloridesalt, 3.0 g (16.6 mmol) of which was suspended in CH₃CN (15 mL), andtreated with triethyl amine (2.3 mL, 16.6 mmol). After 10 min at roomtemperature, 3.6 g (10.0 mmol) of 3S, 4aR, 6S, 8aR ethyl6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) dissolved in CH₃CN (30 mL)followed by K₂CO₃ (2.1 g, 15.0 mmol), was added. The reaction mixturewas heated at 80° C. for 96 h, then the reaction was charged with anadditional portion of cis-hydroxy-L-proline methyl ester hydrochloridesalt (0.35 g) and triethylamine (0.27 mL). After stirring at 80° C. foran additional 24, the reaction was cooled to room temperature andpartitioned between CH₂Cl₂ and H₂O. The aqueous layer was extracted withCH₂Cl₂, and the combined organics were dried (MgSO₄) and concentrated invacuo. The resulting residue was chromatographed (50% EtOAc/hexanefollowed by 10% MeOH/CH₂Cl₂) to provide 1.77 g (50%) of the desiredintermediate title compound.

MS(m/e): 427.8 (M⁺)

Calculated for C₂₁H₃₄N₂O₇: Theory: C, 59.14; H, 8.04; N, 6.57. Found: C,58.84; H, 7.85; N, 6.62

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Methoxycarbonyl)-(4R)₄-bromopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of triphenylphosphine (0.69 g, 2.64 mmol) and Br₂ (0.14 mL,2.64 mmol) dissolved in CH₂Cl₂ (5 mL) was stirred at room temperaturefor 0.25 h. A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(methoxycarbonyl)-(4S)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.75 g, 1.76 mmol), the compound of Step A above, and pyridine (0.29mL, 3.52 mmol) dissolved in CH₂Cl₂ (10 mL), was added, and the reactionwas stirred at room temperature for 21 h. The reaction was partitionedbetween CH₂Cl₂ and 10% aqueous NaHSO₄, the aqueous layer was extractedwith CH₂Cl₂, and the combined organics were dried (MgSO₄) andconcentrated in vacuo. Diethyl ether was added, and residualtriphenylphosphine oxide was removed by vacuum filtration. After rotaryevaporation, the resulting residue was chromatographed (50% EtOAc/hexanethen 5% MeOH/CH₂Cl₂) to provide 0.43 g (50%) of the desired intermediatetitle compound:

MS(m/e): 489.3 (M⁺)

Calculated for C₂₁H₃₅BrN₂O₆.0.5H₂O: Theory: C, 50.61; H, 6.88; N, 5.62.Found: C, 50.89; H, 6.65; N, 5.62

C. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-bromopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(methoxycarbonyl)-(4R)₄-bromopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.43 g, 0.88 mmol), the compound of Step B above, dissolved in 5 Naqueous HCl (10 mL) was heated at 70° C. for 48 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.20 g, 58%) as a white foam:

MS(m/e): 389.1 (M⁺)

Calculated for C₁₆H₂₅BrN₂O₄: Theory: C, 49.37; H, 6.47; N, 7.20. Found:C, 49.78; H, 6.48; N, 6.77

¹³C NMR (D₂O): δ 175.6, 173.0, 70.1, 65.1, 63.7, 56.3, 55.0, 43.0, 40.3,35.1, 33.1, 32.7, 31.1, 28.7, 27.5, 24.8 ppm

EXAMPLE 7 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-iodopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-iodopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of triphenylphosphine (0.61 g, 2.3 mmol), 12 (0.59 mL, 2.3mmol), and imidazole (0.16 g, 2.3 mmol), dissolved in CH₂Cl₂ (20 mL) wasstirred at room temperature for 0.25 h. A solution of 3S, 4aR, 6S, 8aRethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)₄-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step B described in the preparation of Example 1 above(0.68 g, 1.5 mmol), dissolved in CH₂Cl₂ (10 mL), was added, and thereaction was stirred at room temperature for 18 h. The reaction waspartitioned between CH₂Cl₂ and 10% aqueous NaHSO₄, the aqueous layer wasextracted with CH₂Cl₂, and the combined organics were dried (MgSO₄) andconcentrated in vacuo. The resulting residue was chromatographed (50%EtOAc/hexane) to provide 0.52 g (61%) of the desired intermediate titlecompound:

MS(m/e): 551.3 (M⁺)

Calculated for C₂₂H₃₅₁N₂O₆: Theory: C, 48.01; H, 6.41; N, 5.09. Found:C, 48.02; H, 6.27; N, 4.81

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)₄-iodopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid.

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)₄-iodopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.51 g, 0.93 mmol), the compound of Step A above, dissolved in 5 Naqueous HCl (20 mL) was heated at 100° C. for 12 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.37 g, 91%) as a white foam:

MS(m/e): 437.2 (M⁺)

Calculated for C₁₆H₂₅IN₂O₄: Theory: C, 44.05; H, 5.78; N, 6.42. Found:C, 44.31; H, 5.80; N, 6.38

EXAMPLE 8 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-chloropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)₄-chloropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of triphenylphosphine (0.67 g, 2.55 mmol) and CCl₄ (0.25 mL,2.55 mmol) dissolved in CH₂Cl₂ (10 mL) was stirred at room temperaturefor 0.25 h. A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step B described in the preparation of Example 1 above(0.75 g, 1.70 mmol), dissolved in CH₂Cl₂ (10 mL) was added, and thereaction was stirred at room temperature for 18 h. Additionaltriphenylphosphine (0.77 mmol) and CCl₄ (0.77 mmol) were added, and thereaction was heated at 40° C. for 5 h. The reaction was partitionedbetween CH₂Cl₂ and 10% aqueous NaHSO₄, the aqueous layer was extractedwith CH₂Cl₂, and the combined organics were dried (MgSO₄) andconcentrated in vacuo. The resulting residue was chromatographed (50%EtOAc/hexane) to provide 0.59 g (76%) of the desired intermediate titlecompound:

MS(m/e): 459.5 (M⁺)

Calculated for C₂₂H₃₅ClN₂O₆: Theory: C, 57.57; H, 7.69; N, 6.10. Found:C, 57.64; H, 7.58; N, 5.88

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylic acid)-(4S)_(t)chloropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-chloropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.58 g, 1.26 mmol), the compound of Step A above, dissolved in 5 Naqueous HCl (20 mL) was heated at 100° C. for 12 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.38 g, 87%) as a white foam:

MS(m/e): 345.1 (M⁺)

Calculated for C₁₆H₂₅ClN₂O₄.0.25H₂O: Theory: C, 55.01; H, 7.36; N, 8.02.Found: C, 54.71; H, 7.26; N, 7.76

¹³C NMR (D₂O): δ 183.1, 181.3, 70.4, 63.5, 62.8, 56.3, 44.3, 41.5, 37.5,36.8, 34.9, 34.7, 31.2, 29.4, 27.2 ppm

EXAMPLE 9 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)₄-bromopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-Ethoxycarbonyl)-(4R)₄hydroxypyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step B described in the preparation of Example 1 above(1.5 g, 3.4 mmol), cooled to 0° C. in CH₂Cl₂ (10 mL) was addediodotrimethylsilane (1.45 mL, 10.2 mmol). The reaction was warmed toroom temperature, stirred for 3 h, and then quenched by the addition ofsaturated aqueous NaHCO₃. The reaction was partitioned between CH₂Cl₂and 10% aqueous NaHSO₄, the aqueous layer was extracted with CH₂Cl₂, andthe combined organics were dried (MgSO₄) and concentrated in vacuo toprovide 1.22 g (94%) of the desired intermediate title compound.

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-2-(tert-butoxycarbonyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step A described in the preparation above (1.22 g, 3.19mmol), dissolved in THF (10 mL) was added a solution of 1N aqueoussodium hydroxide (10 mL) followed by di-tert-butyl dicarbonate (1.04 g,4.78 mmol). The reaction was stirred for 1.5 h, then partitioned betweenCH₂Cl₂ and H₂O. The aqueous layer was extracted with CH₂Cl₂, and thecombined organics were dried (MgSO₄) and concentrated in vacuo. Columnchromatography (EtOAc, then 5% MeOH/CH₂Cl₂) provided 1.04 g (68%) of thedesired intermediate title compound.

C. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-bromopyrrolidinyl)methyl)-2-(tert-butoxycarbonyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of triphenylphosphine (0.85 g, 3.23 mmol) and Br₂ (0.17 mL,3.23 mmol) dissolved in CH₂Cl₂ (5 mL) was stirred at room temperaturefor 0.25 h. A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-2-(tert-butoxycarbonyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(1.04 g, 2.15 mmol), the compound of Step B above, and pyridine (0.35mL, 4.30 mmol) dissolved in CH₂Cl₂ (15 mL) was added, and the reactionwas stirred at room temperature for 20 h. The reaction was partitionedbetween CH₂Cl₂ and 10% aqueous NaHSO₄, the aqueous layer was extractedwith CH₂Cl₂, and the combined organics were dried (MgSO₄) andconcentrated in vacuo. Ether was added, and residual triphenylphosphineoxide was removed by vacuum filtration. After rotary evaporation, theresulting residue was chromatographed (25% EtOAc/hexane) to provide 0.62g (53%) of the desired intermediate title compound:

MS(m/e): 545.5 (M)

D. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-bromopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-bromopyrrolidinyl)methyl)-2-(tert-butoxycarbonyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.62 g, 1.14 mmol), the compound of Step C above, was dissolved in 1 NHCl/EtOAc, and stirred at room temperature for 20 h. The reaction wasconcentrated in vacuo, then acetone was added and subsequently removedin vacuum filtration to provide 0.55 g (100%) of the desiredintermediate title compound:

MS(m/e): 445.2 (M⁺)

Calculated for C₂₀H₃₃BrCl₂N₂O₄.2.0H₂O: Theory: C, 43.49; H, 6.75; N,5.07. Found: C, 43.76; H, 6.52; N, 4.96

E. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-bromopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-bromopyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.35 g, 0.68 mmol), the compound of Step D above, dissolved in 5 Naqueous HCl (15 mL) was heated at 70° C. for 12 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.20 g, 76%) as a white foam:

MS(m/e): 389.0 (M⁺)

Calculated for C₁₆H₂₅BrN₂O₄.0.5H₂O: Theory: C, 48.25; H, 6.58; N, 7.03.Found: C, 48.50; H, 6.65; N, 7.07

¹³C NMR (D₂O): δ 175.3, 173.9, 70.1, 64.9, 63.0, 54.8, 44.3, 43.0, 40.2,35.0, 32.8, 32.7, 31.1, 28.7, 27.5, 24.7 ppm

EXAMPLE 10 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(2-methyl-2H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-(methanesulfonyloxy)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step B described in the preparation of Example 1 above(5.0 g, 11.3 mmol), cooled to 0° C. in CH₂Cl₂ (25 mL), was addedtriethylamine (1.90 mL, 13.6 mmol) followed by methanesulfonyl chloride(1.05 mL, 13.6 mmol). The reaction was warmed to room temperature,stirred for 20 h, and then quenched by the addition of 10% aqueousNaHSO₄. The aqueous layer was extracted with CH₂Cl₂, and the combinedorganics were dried (MgSO₄) and concentrated in vacuo. Columnchromatography (50% EtOAc/hexane) provided 3.3 g (57%) of the desiredintermediate title compound.

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-(2H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-(methanesulfonyloxy)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step A described in the preparation above (2.0 g, 3.86mmol), dissolved in acetonitrile (6 mL), was added thiotetrazole (1.18g, 11.6 mmol) followed by potassium carbonate (0.80 g, 5.79 mmol). Thereaction was heated at 80° C. for 60 h, then partitioned between CH₂Cl₂and H₂O. The aqueous layer was extracted with CH₂Cl₂, and the combinedorganics were dried (MgSO₄) and concentrated in vacuo. Columnchromatography (75% EtOAc/hexane, then 5% EtOH/CH₂Cl₂) provided 0.96 g(47%) of the desired intermediate title compound.

C. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-(2-methyl-2H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of the compound of Step B above (0.48 g, 0.92 mmol),dissolved in THF (5 mL), was charged with NaH (60% dispersion in mineraloil) (0.04 g, 0.92 mmol), and stirred at room temperature for 10 min.Iodomethane (0.05 mL, 0.87 mmol) was added, and the reaction was heatedat 45° C. for 48 h. The reaction was partitioned between CH₂Cl₂ and 10%aqueous NaHSO₄, the aqueous layer was extracted with CH₂Cl₂, and thecombined organics were dried (MgSO₄) and concentrated in vacuo. Theresulting residue was chromatographed (Stepwise gradient: 20%-50%EtOAc/hexane) to provide 0.16 g (32%) of the desired intermediate titlecompound (Isomer 1), as well as 0.10 g (20%) of the 1-methyl-tetrazoleregioisomer (Isomer 2):

MS(m/e): 539.1 (M⁺)

D. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(2-methyl-2H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-(2-methyl-2H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.16 g, 0.30 mmol), Isomer 1 of Step C above, dissolved in 5 N aqueousHCl (10 mL), was heated at 90° C. for 20 h. The reaction mixture wascooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.11 g, 87%) as a white foam:

MS(m/e): 425.2 (M⁺)

Calculated for C₁₈H₂₈N₆O₄S.0.5H₂O: Theory: C, 49.87; H, 6.74; N, 19.39.Found: C, 50.06; H, 6.59; N, 18.68

¹³C NMR D₂O): δ 175.0, 172.4, 161.3, 69.8, 62.2, 59.8, 54.4, 42.5, 41.6,40.4, 35.4, 34.5, 32.4, 32.2, 30.7, 28.3, 27.0, 24.4 ppm

EXAMPLE 11 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(1-methyl-1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-(1-methyl-1H-tetrazol-5-ylsulfonyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.10 g, 0.19 mmol), Isomer 2 from Step C of Example 10 above, dissolvedin 5 N aqueous HCl (10 mL), was heated at 90° C. for 20 h. The reactionmixture was cooled to room temperature and concentrated in vacuo. Theresulting crude foam was dissolved in H₂O (50 mL) and stirred in thepresence of Dowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. Theresin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O, thenstirred in the presence of 10% pyridine/H₂O (75 mL) for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.08 g, 95%) as awhite foam:

MS(m/e): 425.2 (M⁺)

Calculated for C₁₈H₂₈N₆O₄S.0.75H₂O: Theory: C, 49.36; H, 6.79; N, 19.19.Found: C, 49.08; H, 6.58; N, 18.39

¹³C NMR (D₂O): δ 174.9, 172.3, 153.6, 69.8, 62.1, 60.1, 54.4, 42.5,42.3, 35.5, 34.5, 34.3, 32.4, 32.2, 30.7, 28.3, 27.0, 24.4 ppm

EXAMPLE 12 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-bromopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of triphenylphosphine (0.89 g, 3.40 mmol) and Br₂ (0.17 mL,3.40 mmol) dissolved in CH₂Cl₂ (5 mL) was stirred at room temperaturefor 0.25 h. A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)₄-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(1.00 g, 2.27 mmol), the compound of Step B described in the preparationof Example 1 above, and pyridine (0.37 mL, 4.54 mmol) dissolved inCH₂Cl₂ (10 mL), was added, and the reaction was stirred at roomtemperature for 20 h. The reaction was partitioned between CH₂Cl₂ and10% aqueous NaHSO₄, the aqueous layer was extracted with CH₂Cl₂, and thecombined organics were dried (MgSO₄) and concentrated in vacuo. Afterrotary evaporation, the resulting residue was chromatographed (25%EtOAc/hexane) to provide 0.66 g (58%) of the desired intermediate titlecompound.

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of the compound of Step A described in the preparationabove (0.66 g, 1.31 mmol), dissolved in acetonitrile (2 mL), was addedthiotriazole (0.40 g, 3.93 mmol) followed by potassium carbonate (0.27g, 1.97 mmol). The reaction was heated at 80° C. for 96 h, thenpartitioned between CH₂Cl₂ and H₂O. The aqueous layer was extracted withCH₂Cl₂, and the combined organics were dried (MgSO₄) and concentrated invacuo. Column chromatography (50% EtOAc/hexane, then 5% EtOH/CH₂Cl₂)provided 0.60 g (87%) of the desired intermediate title compound:

MS(m/e): 524.3 (M⁺)

Calculated for C₂₄H₃₇N₅O₆S.0.75H₂O: Theory: C, 53.67; H, 7.22; N, 13.04.Pound: C, 53.64; H, 6.91; N, 12.94

C. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.59 g, 1.13 mmol), the compound of Step B above, dissolved in 5 Naqueous HCl (15 mL), was heated at 90° C. for 20 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.36 g, 78%) as a white foam:

MS(m/e): 410.3 (M⁺)

Calculated for C₁₈H₂₇N₅O₄S.0.25H₂O: Theory: C, 52.22; H, 6.70; N, 16.92.Found: C, 52.00; H, 6.70; N, 16.55

EXAMPLE 13 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-(methanesulfonyloxy)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step B described in the preparation of Example 10 above(1.0 g, 1.93 mmol), dissolved in acetonitrile (2 mL) was addedthiotriazole (0.58 g, 5.78 mmol) followed by potassium carbonate (0.40g, 2.90 mmol). The reaction was heated at 80° C. for 48 h, thenpartitioned between CH₂Cl₂ and H₂O. The aqueous layer was extracted withCH₂Cl₂, and the combined organics were dried (MgSO₄) and concentrated invacuo. Column chromatography (50% EtOAc/hexane, then 5% MeOH/CH₂Cl₂)provided 0.87 g (86%) of the desired intermediate title compound:

MS(m/e): 524.4 (M⁺)

Calculated for C₁₈H₂₇N₅O₄S.0.5H₂O: Theory: C, 54.12; H, 7.19; N, 13.15.Found: C, 54.04; H, 6.85; N, 13.07

¹³C NMR (D₂O): δ 175.1, 172.7, 146.7, 70.1, 69.4, 62.9, 60.1, 54.5,42.5, 41.5, 35.3, 34.5, 32.4, 32.2, 30.7, 28.3, 27.0, 24.4 ppm

D. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)-4-(1H-(1,2,4)triazol-3-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.79 g, 1.51 mmol), the compound of Step A above, dissolved in 5 Naqueous HCl (20 mL), was heated at 90° C. for 17 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (50 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (3 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O (75 mL) for 2 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.60 g, 97%) as a white foam:

MS(m/e): 410.3 (M⁺)

Calculated for C₁₈H₂₇N₅O₄S.0.7H₂O: Theory: C, 51.22; H, 6.78; N, 16.59.Found: C, 51.56; H, 6.65; N, 16.29

¹³C NMR (D₂O): δ 175.1, 172.4, 146.6, 70.1, 69.5, 61.6, 60.0, 54.5,42.5, 41.0, 35.5, 34.6, 32.7, 32.1, 30.7, 28.2, 27.0, 24.1 ppm

EXAMPLE 14 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-(1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-(1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4S)₄-bromopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.64 g, 1.27 mmol), the compound of Step A described in the preparationof Example 12 above, dissolved in acetonitrile (1.25 mL) was addedthiotetrazole (0.52 g, 5.09 mmol) followed by potassium carbonate (0.35g, 2.54 mmol). The reaction was heated at 80° C. for 72 h, thenpartitioned between CH₂Cl₂ and H₂O. The aqueous layer was extracted withCH₂Cl₂, and the combined organics were dried (MgSO₄) and concentrated invacuo. Column chromatography (50% EtOAc/hexane, then 5% EtOH/CH₂Cl₂)provided 0.19 g (29%) of the desired intermediate title compound:

MS(m/e): 525.3 (M⁺)

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-(1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step A above (0.17 g, 0.32 mmol),dissolved in 5 N aqueous HCl (10 mL), was heated at 90° C. for 19 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam was dissolved in H₂O (50 mL) and stirredin the presence of Dowex 50×8 (100-200) ion-exchange resin (3 g) for 2h. The resin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O,then stirred in the presence of 10% pyridine/H₂O (75 mL) for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.10 g, 71%) as awhite foam:

MS(m/e): 411.2 (M⁺)

EXAMPLE 15 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(Carboxylic acidmethylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of Ethyl 2S,4S-4-Acetylsulfanylpyrrolidine-1-(tert-butoxycarbonyl)-2-carboxylate

A solution of cis-4-hydroxy-L-proline-hydrochloride (3.0 g, 15.3 mmol)dissolved in CH₂Cl₂ (25 mL) was stirred at room temperature in thepresence of triethylamine (6.4 mL, 46.0 mmol). After 0.25 h,di-tert-butyl dicarbonate (4.2 mL, 18.4 mmol) was added. The reactionwas stirred at room temperature for 22 h, then partitioned between Et₂Oand H₂O. The organic layer was dried over MgSO₄ and concentrated invacuo. Column chromatography (10% MeOH/CH₂Cl₂) provided 4.0 g (93%) ofethyl 2S, 4R-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylate.

A solution of triphenylphosphine (8.1 g, 30.8 mmol) and diethylazodicarboxylate (4.1 mL, 30.8 mmol) cooled to 0° C. in THF (50 mL) wasstirred for 0.5 h, whereupon ethyl 2S,4R-1-(tert-butoxycarbonyl)₄-hydroxypyrrolidine-2-carboxylate (4.0 g,15.4 mmol), dissolved in THF (20 mL), and thioacetic acid (2.2 mL, 30.8mmol) were added. The reaction was stirred at 0° C. for 1 h, then warmedto room temperature and stirred for an additional 18 h. The reaction wasconcentrated in vacuo, then Et₂O (100 mL) was added, and the residualsolid was removed by vacuum filtration. The filtrate was concentrated invacuo and chromatographed (20% EtOAc/hexane) to provide 4.40 g (90%) ofthe intermediate title compound.

B. Preparation of Ethyl 2S,4S-4-Ethoxycarbonylmethylsulfanylpyrrolidine-2-carboxylate

To a solution of the intermediate of Step A described above (2.20 g,6.93 mmol) dissolved in MeOH (20 mL) was added a solution of 1N aqueousNaOH (7.6 mL, 7.6 mmol), followed, after 0.5 h, by ethyl bromoacetate(0.84 mL, 7.6 mmol). The reaction was stirred at room temperature for 2h, then partitioned between CH₂Cl₂ and 10% saturated aqueous NaHSO₄. Theaqueous layer was extracted with CH₂Cl₂, and the combined organics weredried (MgSO₄) and concentrated in vacuo. Column chromatography (25%EtOAc/hexane) provided 2.0 g (5.5 mmol) of the BOC-protectedintermediate. This material was dissolved in 1 N HCl/EtOAc (20 mL), thereaction was stirred at room temperature for 42 h, then concentrated.Acetone was added, then removed in vacuo. The residue was taken up in asolution of 2 M NH₃/EtOH (5 mL), the resulting salt was removed byvacuum filtration, and the filtrate was concentrated in vacuo. Columnchromatography (50% EtOAc/hexane) provided the titled intermediate (1.28g, 95%).

C. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-(Ethoxycarbonylmethylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 1.0 g (2.2 mmol) of 3S, 4aR, 6S, 8aR ethyl6-((4-methylphenyl)sulfonyloxy)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step A of Example 1 described above, dissolved in CH₃CN(2.0 mL) was added K₂CO₃ (0.46 g, 3.3 mmol) followed by ethyl 2S,4S-4-ethoxycarbonylmethylsulfanylpyrrolidine-2-carboxylate, the compoundof Step B above (0.81 g, 3.1 mmol). The reaction mixture was heated at80° C. for 72 h, cooled to room temperature, then partitioned betweenCH₂Cl₂ and H₂O. The aqueous layer was extracted with CH₂Cl₂, and thecombined organics were dried (MgSO₄), and concentrated. The resultingresidue was chromatographed (50% EtOAc/hexane) to provide 0.88 g (74%)of the desired intermediate title compound:

MS(m/e): 543.3 (M⁺)

Calculated for C₂₆H₄₂N₂O₈S: Theory: C, 57.54; H, 7.80; N, 5.16. Found:C, 57.57; H, 7.67; N, 5.22

D. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(Carboxylic acidmethylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step C above (0.87 g, 0.1.6 mmol),dissolved in 5 N aqueous HCl (20 mL), was heated at 90° C. for 18 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam was dissolved in H₂O (50 mL) and stirredin the presence of Dowex 50×8 (100-200) ion-exchange resin (3 g) for 2h. The resin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O,then stirred in the presence of 10% pyridine/H₂O (75 mL) for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.53 g, 83%) as awhite foam:

MS(m/e): 401.2 (M⁺)

Calculated for C₁₈H₂₈N₂O₆S.0.5H₂O: Theory: C, 52.79; H, 7.14; N, 6.84.Found: C, 52.74; H, 6.80; N, 6.65

¹³C NMR (D₂O): δ 176.0, 175.2, 173.4, 70.1, 63.0, 60.9, 54.7, 43.0,41.7, 36.2, 35.3, 34.9, 32.7, 32.6, 31.1, 28.8, 27.5, 24.9 ppm

EXAMPLE 16 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(methylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of Ethyl 2S, 4S-4-Methylsulfanylpyrrolidine-2-carboxylate

To a solution of the intermediate of Step A described in the preparationof Example 15 above (2.2 g, 6.9 mmol) dissolved in MeOH (20 mL) wasadded a solution of 1N aqueous NaOH (7.6 mL, 7.6 mmol), followed, after0.5 h, by dimethylsulfate (0.72 mL, 7.6 mmol). The reaction was stirredat room temperature for 2 h, then partitioned between CH₂Cl₂ and 10%saturated aqueous NaHSO₄. The aqueous layer was extracted with CH₂Cl₂,and the combined organics were dried (MgSO₄) and concentrated in vacuo.Column chromatography (25% EtOAc/hexane) provided 1.6 g (5.4 mmol) ofthe BOC-protected intermediate. This material was dissolved in 1 NHCl/EtOAc (17.4 mL), the reaction was stirred at room temperature for 42h, then concentrated. Acetone was added, then removed in vacuo. Theresidue was taken up in a solution of 2 M NH3/EtOH (5 mL), the resultingsalt was removed by vacuum filtration, then the filtrate wasconcentrated in vacuo. Column chromatography (50% EtOAc/hexane then 5%MeOH(CH₂Cl₂) provided the titled intermediate (0.73 g, 89%).

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-(methylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 1.0 g (2.2 mmol) of 3S, 4aR, 6S, 8aR ethyl6-((4-methylphenyl)sulfonyloxy)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,the compound of Step A of Example 1 described above, dissolved in CH₃CN(2.0 mL) was added K₂CO₃ (0.46 g, 3.3 mmol), followed by ethyl 2S,4S-4-methylsulfanylpyrrolidine-2-carboxylate, the compound of Step Aabove (0.73 g, 3.9 mmol). The reaction mixture was heated at 80° C. for72 h, cooled to room temperature, then partitioned between CH₂Cl₂ andH₂O. The aqueous layer was extracted with CH₂Cl₂, and the combinedorganics were dried (MgSO₄), and concentrated. The resulting residue waschromatographed (50% EtOAc/hexane) to provide 0.78 g (75%) of thedesired intermediate title compound:

MS(m/e): 471.3 (M⁺)

Calculated for C₂₃H₃₈N₂O₆S.0.5H₂O: Theory: C, 57.60; H, 8.20; N, 5.84.Found: C, 57.23; H, 7.96; N, 6.03

C. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(methylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step B above (0.77 g, 0.1.6 mmol),dissolved in 5 N aqueous HCl (25 mL), was heated at 80° C. for 72 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam-was dissolved in H₂O (50 mL) and stirredin the presence of Dowex 50×8 (100-200) ion-exchange resin (3 g) for 2h. The resin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O,then stirred in the presence of 10% pyridine/H₂O (75 mL) for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.45 g, 77%) as awhite foam:

MS(m/e): 357.3 (M⁺)

Calculated for C₁₈H₂₈N₂O₆S.0.25H₂O: Theory: C, 56.57; H, 7.96; N, 7.76.Found: C, 56.37; H, 7.85; N, 7.72

¹³C NMR (D₂O): δ 175.6, 173.7, 70.2, 63.0, 60.7, 54.9, 43.0, 42.5, 35.8,34.9, 32.9, 32.7, 31.1, 28.8, 27.5, 24.9, 14.5 ppm

EXAMPLE 17 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4S)-4-(1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2S)-2-(ethoxycarbonyl)-(4R)-4-bromopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.79 g, 1.57 mmol), the compound of Step B described in the preparationof Example 6 above, dissolved in acetonitrile (1.5 mL) was addedthiotetrazole (0.64 g, 6.28 mmol) followed by potassium carbonate (0.43g, 3.14 mmol). The reaction was heated at 80° C. for 120 h, thenpartitioned between CH₂Cl₂ and H₂O. The aqueous layer was extracted withCH₂Cl₂, and the combined organics were dried (MgSO₄) and concentrated invacuo. Column chromatography (50% EtOAc/hexane, then 5% EtOH/CH₂Cl₂)provided 0.44 g (53%) of the desired intermediate title compound:

MS(m/e): 525.3 (M⁺)

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4S)-4-(1H-tetrazol-5-ylsulfanyl)pyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step A above (0.30 g, 0.57 mmol),dissolved in 5 N aqueous HCl (15 mL), was heated at 90° C. for 18 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam was dissolved in H₂O (50 mL) and stirredin the presence of Dowex 50×8 (100-200) ion-exchange resin (3 g) for 2h. The resin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O,then stirred in the presence of 10% pyridine/H₂O (75 mL) for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.23 g, 98%) as awhite foam:

MS(m/e): 411.2 (M⁺)

¹³C NMR (D₂O): δ 183.3, 181.3, 149.5, 70.9, 62.5, 61.0, 56.3, 44.3,42.4, 38.1, 37.5, 36.9, 35.0, 34.6, 31.2, 29.4, 27.2 ppm

EXAMPLE 18 Preparation of 3S, 4aR, 6S, 8aR 6-(((2R)-2-(Carboxylicacid)-4,4-difluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2R)-(Ethoxycarbonyl)-(4S)-4-hydroxypyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of cis-4-hydroxy-D-proline methyl ester-hydrochloride (4.0 g,2.1 mmol) dissolved in acetonitrile (20 mL) was stirred in the presenceof triethylamine (3.1 mL, 22.1 mmol) for 0.25 h. A solution of 4.0 g(111.0 mmol) of 3S, 4aR, 6S, 8aR ethyl6-bromomethyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) dissolved in CH₃CN (30 mL) wasadded, followed by potassium carbonate (2.3 g, 2.28 mmol). The reactionwas heated at reflux for 96 h, the reaction mixture was cooled to roomtemperature, then partitioned between CH₂Cl₂ and H₂O. The aqueous layerwas extracted two times with CH₂Cl₂ and the combined organics were driedover MgSO₄, filtered, and concentrated in vacuo. Column chromatography(50% EtOAc/hexane followed by 10% MeOH/CH₂Cl₂) gave 1.92 g (41%) of thedesired intermediate title compound as a colorless oil:

MS(m/e): 427.3 (M⁺)

Calculated for C₂₁H₃₄N₂O₇: Theory: C, 59.14; H, 8.04; N, 6.57. Found: C,58.85; H, 7.83; N, 6.62

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2R)-2-(Ethoxycarbonyl)-4-oxopyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of DMSO (0.63 mL, 8.80 mmol) cooled to −78° C. in CH₂Cl₂(10 mL) was added, dropwise, oxalyl chloride (0.37 mL, 4.20 mmol). Thereaction mixture was stirred for 5 min, then the compound of Step Aabove (1.5 g, 3.52 mmol) dissolved in 10 mL of CH₂Cl₂ was added. Uponstirring for 45 min at −78° C., triethylamine (2.45 mL, 17.6 mmol) wasadded. The reaction was warmed to room temperature over approximately 2hours, and quenched by the addition of 10% aqueous NaHSO₄. The aqueouslayer was extracted with CH₂Cl₂ and the combined organics were driedover MgSO₄, filtered, and concentrated in vacuo. Column chromatography(50% EtOAc/hexane) provided 0.57 g (38%) of the desired intermediatetitle compound as a colorless oil.

C. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2R)-2-(Ethoxycarbonyl)-4,4-difluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a mixture of the compound of Step B above (0.57 g, 1.34 mmol) cooledto −78° C. in CH₂Cl₂ (10 mL) was added, dropwise, diethylaminosulfurtrifluoride (0.44 mL, 3.36 mmol). The reaction was allowed to warm toroom temperature, stirred an additional 55 h, then quenched by theaddition of MeOH. After concentrating in vacuo, the residue waspartitioned between CH₂Cl₂ and saturated aqueous NaHCO₃. The aqueouslayer was extracted with CH₂Cl₂ and the combined organics were driedover MgSO₄, filtered, and concentrated in vacuo. Column chromatography(stepwise gradient: 10-50% EtOAc/hexane) provided 0.51 g (85%) of thedesired intermediate title compound as a colorless oil:

MS(m/e): 447.2 (M⁺)

Calculated for C₂₁H₃₂F₂N₂O₆.0.5H₂O: Theory: C, 55.38; H, 7.30; N, 6.16.Found: C, 55.71; H, 7.03; N, 6.29

D. 3S, 4aR, 6S, 8aR 6-(((2R)-2-(Carboxylicacid)-4,4-difluoropyrrolidinyl)methyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of 3S, 4aR, 6S, 8aR ethyl6-(((2R)-2-(ethoxycarbonyl)-4,4-difluoropyrrolidinyl)methyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.49 g, 1.10 mmol), the compound of Step C above, dissolved in 5 Naqueous HCl (15 mL) was heated at 90° C. for 18 h. The reaction mixturewas cooled to room temperature and concentrated in vacuo. The resultingcrude foam was dissolved in H₂O (75 mL) and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin (10 g) for 2 h. The resin wasfiltered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirred inthe presence of 10% pyridine/H₂O for 2 h. After filtration, the resinwas washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (0.26 g, 68%) as a white foam:

MS(m/e): 345.1 (M⁺)

Calculated for C₁₆H₂₄F₂N₂O₄.0.5H₂O: Theory: C, 54.07; H, 7.09; N, 7.88.Found: C, 53.77; H, 6.93; N, 7.85

¹³C NMR (D₂O): δ 174.8, 171.1, 125.6 (t, J_(C-F)=249.6 Hz), 68.1, 63.2,59.4 (t, J_(C-F)=33.9 Hz), 54.3, 42.5, 37.5 (t, J_(C-F)=24.9 Hz), 34.3,32.3, 32.4, 30.6, 28.5, 16.9, 24.1 ppm

EXAMPLE 19 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5S)-5-hyroxypiperidinyl)-1, 2, 3, 4, 4a, 5, 6, 7, 8,8a-decahydroisoquinoline-3-carboxylic Acid

A. Preparation and resolution of 3R, 5S ethyl5-hydroxypiperidine-3-carboxylate and 3S, 5R ethyl5-hydroxypiperidine-3-carboxylate

Anhydrous HCl was bubbled through a suspension of(O)-5-hydroxypiperidine-3-carboxylic acid (5.6 g, 38.6 mmol) (accordingto the procedures as disclosed in J. Med. Chem., 25, 1157-1162, (1982)),cooled to O ° C. in EtOH (100 mL), until saturation was reached. Thereaction mixture was warmed to room temperature, stirred overnight, thenconcentrated in vacuo. The crude salt was cooled to 0° C. in CHCl₃ (80mL), and anhydrous NH3 was bubbled through the solution. The resultingwhite precipitate was removed by vacuum filtration, and the filtrate wasconcentrated in vacuo to provide 6.6 g (99%) of (±) ethyl5-hydroxypiperidine-3-carboxylate as a pale yellow oil.

To a solution of (±) ethyl 5-hydroxypiperidine-3-carboxylate (1.00 g,5.77 mmol) dissolved in 95% EtOH (8.0 mL) was added p-toluoyl-D-tartaricacid (2.20 g, 5.77 mmol). Following complete dissolution of the acid,the solution remained at room temperature overnight. The resultingcrystals were filtered and washed with cold 95% EtOH to provide 581 mg(1.04 mmol, 18%, 95% ee) of 3R,5S-(+) ethyl5-hydroxypiperidine-3-carboxylate as the tartrate salt. Resolution toprovide 3S,5R-(−) ethyl 5-hydroxypiperidine-3-carboxylate was performedin an analogous fashion, using p-toluoyl-L-tartaric acid. The absoluteconfiguration of this isomer was assigned by x-ray crystallography.

Determination of % ee: A solution of 10 mg of the resulting salt (0.018mmol), potassium carbonate (8 mg, 0.054 mmol), and (S)-(−)-MTPA (4 mL,0.022 mmol), was stirred for 2 h at room temperature in 1 mL of 1:1THF/H₂O. An aliquot of the reaction was removed and analyzed byreverse-phase HPLC (Hypersil BDS-C18 column, using a 0.1% TFA/ACN-0.1%TFA/H20 gradient system): RT 52.0 min for (+) enantiomer, 53.2 min for(−) enatiomer.

B. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3R)-(Ethoxycarbonyl)-(5S)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of 3R,5S-(+) ethyl 5-hydroxypiperidine-3-carboxylate (0.37 g,2.13 mmol), 3S, 4aS, 8aS-(−) ethyl2-methoxycarbonyl-6-oxodecahydroisoquinoline-3-carboxylate (1.21 g, 4.27mmol) (prepared by one of ordinary skill in the art following theprocedures as disclosed in U.S. Pat. No. 5,670,516), NaBH(OAc)₃ (0.90 g,4.27 mmol), and HOAc (0.25 mL, 4.27 mmol) was stirred at roomtemperature in THF (15 mL) for 72 h. The reaction mixture waspartitioned between 3:1 CHCl₃/IPA and saturated aqueous NaHCO₃,extracted with CHCl₃/EPA, washed with saturated aqueous NaCl, dried(NgSO₄), and concentrated. Chromatography (Stepwise gradient: CH₂Cl₂-5%MeOH/CH₂Cl₂) provided the titled compound (0.48 g, 52%):

MS(m/e): 441.3 (M⁺)

Calculated for C₂₂H₃₆N₂O₇: Theory: C, 59.98; H, 8.24; N, 6.36. Found: C,59.86; H, 8.00; N, 6.41

C. Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5S)-5-hydroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step B above (205 mg, 0.46 mmol) dissolvedin 5 N aqueous HCl (10 mL) was heated at 95° C. for 12 h. The reactionmixture was cooled to room temperature and concentrated in vacuo. Theresulting crude foam was dissolved in H₂O and stirred in the presence ofDowex 50×8 (100-200) ion-exchange resin for 4 h. The resin was filtered,washed sequentially with 1:1 THF/H₂O and H₂O, then stirred in thepresence of 10% pyridine/H₂O for 12 h. After filtration, the resin waswashed with H₂O, and the filtrate was concentrated in vacuo to providethe title compound (123 mg, 82%) as a white foam:

MS(m/e): 327.3 (M⁺)

Calculated for C₁₆H₂₆N₂O₅.0.75H₂O: Theory: C, 56.54; H, 8.16; N, 8.24.Found: C, 56.34; H, 8.02; N, 8.09

¹³C NMR (D₂O): □ 182.2, 175.9, 67.0, 63.3, 55.2, 54.7, 51.3, 43.5, 42.7,36.9, 32.9, 32.8, 31.1, 27.1, 26.3, 22.0 ppm

EXAMPLE 20 Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5R)-5-hydroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3S)-(Ethoxycarbonyl)-(5R)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

Employing the same method described for the preparation of the compoundin Step B of Example 19, using 3S, 5R (−) ethyl5-hydroxypiperidine-3-carboxylate, the preparation of which is describedin Step A of Example 19, provided the title compound:

MS(m/e): 441.3 (M+)

Calculated for C₂₂H₃₆N₂O₇: Theory: C, 59.98; H, 8.24; N, 6.36. Found: C,60.40; H, 8.18; N, 6.47

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5R)-5-hydroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step A above (140 mg, 0.0.32 mmol)dissolved in 5 N aqueous HCl (10 mL) was heated at 95° C. for 12 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam was dissolved in H₂O and stirred in thepresence of Dowex 50×8 (100-200) ion-exchange resin for 4 h. The resinwas filtered, washed sequentially with 1:1 THF/H₂O and H₂O, then stirredin the presence of 10% pyridine/H₂O for 12 h. After filtration, theresin was washed with H₂O, and the filtrate was concentrated in vacuo toprovide the title compound (84 mg, 81%) as a white foam:

MS(m/e): 327.3 (M⁺)

Calculated for C₁₆H₂₆N₂O₅1.5H₂O: Theory: C, 54.38; H, 8.27; N, 7.93.Found: C, 54.69; H, 8.08; N, 7.62

¹³C NMR D₂O): □182.5, 67.2, 63.9, 55.8, 55.3, 51.6, 43.8, 43.7, 37.0,36.1, 34.3, 34.0, 28.3, 27.0, 22.9 ppm

EXAMPLE 21 Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5S)-5-hydroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3S)-(Ethoxycarbonyl)-(5S)-5-benzoyloxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of 3S, 4aR, 6S, 8aR ethyl6-((3S)-(ethoxycarbonyl)-(5S)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.52 g, 1.16 mmol), the compound of Step A described in the preparationof Example 20 above, cooled to 0° C. in THF (10 mL) was charged withtriphenylphospine (1.22 g, 4.68 mmol), benzoic acid (0.57 g, 4.68 mmol),and diethyl azodicarboxylate (0.68 g, 4.68 mmol). After stirring at roomtemperature for 48 h, the reaction mixture was loaded onto a 5 g SCXMega Bond Elut SPE cartridge (Varian Sample Preparation Products) andeluted with EtOH, followed by CH₂Cl₂. The product was removed with 2 MNH3/EtOH, and the solution was concentrated then chromatographed(stepwise gradient: hexane-50% EtOAc/hexane), providing the intermediatetitle compound (0.51 g, 81%).

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5S)-5-hydroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound of Step A above (276 mg, 0.51 mmol) dissolvedin 5 N aqueous HCl (15 mL) was heated at 95° C. for 12 h. The reactionmixture was cooled to room temperature and concentrated in vacuo. Theresulting crude foam was dissolved in H₂O and loaded onto a 5 g SCX MegaBond Elut SPE cartridge. The cartridge was washed sequentially with H₂O,1:1 THF/H₂O, and H₂O. The product was removed with 1:1 pyridine/H₂O, andconcentrated to provide the title compound (139 mg, 84%) as a whitefoam:

MS(m/e): 325.3 (M⁻)

Calculated for C₁₆H₂₆N₂O₅.1.2H₂O: Theory: C, 55.23; H, 8.23; N, 8.05.Found: C, 54.87; H, 8.12; N, 8.09

13C NMR (D₂O): □179.4, 174.7, 65.6, 62.2, 59.3, 54.4, 52.3, 50.8, 43.3,42.2, 32.2, 31.9, 31.1, 30.0, 26.1, 23.3 ppm

EXAMPLE 22 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5R)-5-hyroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3R)-(Ethoxycarbonyl)-(5R)-5-benzoyloxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of 3S, 4aR, 6S, 8aR ethyl6-((3R)-(ethoxycarbonyl)-(5S)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(2.5 g, 5.68 mmol), the compound described in Step B of Example 19, wassubjected to the reaction described in Step A of Example 21 above toprovide the titled intermediate (1.89 g, 61%):

MS(m/e): 545.2 (M⁺)

Calculated for C₂₉H₄₀N₂O₈: Theory: C, 63.95; H, 7.40; N, 5.14. Found: C,63.98; H, 7.34; N, 5.11

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5R)-5-hydroxypiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 327.3 (M⁺)

Calculated for C₁₆H₂₆N₂O₅.0.75H₂O: Theory: C, 56.54; H, 8.16; N, 8.24.Found: C, 56.53; H, 8.09; N, 8.20

¹³C NMR (D₂O): □179.3, 174.7, 66.0, 62.6, 54.4, 52.4, 43.6, 42.2, 32.2,31.8, 31.0, 30.1, 27.5, 26.1, 25.9, 21.0 ppm

EXAMPLE 23 Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5S)-5-fluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3S)-(Ethoxycarbonyl)-(5S)-5-fluoropiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of the compound prepared in Step A of Example 20 (204 mg,0.46 mmol) cooled to −78° C. in CH₂Cl₂ (5 mL) was addeddiethylaminosulfur trifluoride (92 □L, 0.69 mmol). The reaction waswarmed to room temperature, stirred for 48 h, quenched with MeOH, thenconcentrated in vacuo. The residue was partitioned between 3:1 CHCl₃/IPAand saturated aqueous NaHCO₃, extracted with CHCl₃/IPA, washed withsaturated aqueous NaCl, dried (MgSO₄), and concentrated. Chromatography(stepwise gradient: hexane-75% EtOAc/hexane) provided the title compound(147 mg, 72%):

MS(m/e): 444.3 (M+)

Calculated for C₂₂H₃₅FN₂O₆: Theory: C, 59.71; H, 7.97; N, 6.33. Found:C, 60.12; H, 7.99; N, 6.48

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5S)-5-fluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed or the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 329.0 (M⁺)

HRMS (m/z): [M+H]⁺ calcd for C₁₆H₂₅FN₂O₄, 329.1877; found 329.1894

¹³C NMR (D₂O): □ 180.7, 174.7, 87.0 (d, J_(C-F)=171.2 Hz), 81.1 (d,J_(C-F)=170.5 Hz), 69.6 (d, J_(C-F)=207.9 Hz), 65.9, 54.4, 52.8, 49.7,42.2, 32.2, 31.9, 30.1, 25.5, 23.3, 22.0 ppm

EXAMPLE 24 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(55)-5-fluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3R)-(Ethoxycarbonyl)-(5S)-5-fluoropiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-((3R)-(ethoxycarbonyl)-(5R)-5-benzoyloxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(1.2 g, 2.17 mmol), the compound described in Step A of Example 22,dissolved in EtOH (50 mL) was added H₂SO₄ (0.69 g, 6.51 mmol). Thereaction was heated at 80° C. for 72 h, then concentrated in vacuo. Theresidue was partitioned between 3:1 CHCl₃/IPA and 1 N NaOH, extractedwith CHCl₃/EPA, washed with saturated aqueous NaCl, dried (MgSO₄), andconcentrated. Chromatography (Stepwise gradient: CH₂Cl₂-30% MeOH/CH₂Cl₂)provided the N-methyl carbamate diethyl ester intermediate (0.38 g,40%), which was subjected to the DAST fluorination reaction as in thepreparation of the compound described in Step A of Example 23 above,providing the title compound in 85% yield:

MS(m/e): 443.2 (M⁺)

Calculated for C₂₂H₃₅FN₂O₆.0.25H₂O: Theory: C, 59.11; H, 8.00; N, 6.27.Found: C, 58.76; H, 7.54; N, 6.14

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5S)-5-fluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 329.2 (M⁺)

Calculated for C₁₆H₂₅FN₂O.0.75H₂O: Theory: C, 56.21; H, 7.81; N, 8.19.Found: C, 56.03; H, 7.50; N, 7.98

EXAMPLE 25 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5R)-5-fluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3R)-(Ethoxycarbonyl)-(5R)-5-fluoropiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

The compound prepared in Step B of Example 19, 3S, 4aR, 6S, 8aR ethyl6-((3R)-(ethoxycarbonyl)-(5S)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate,was subjected to the DAST fluorination reaction described in thepreparation of the compound described in Step A of Example 23 above toprovide the title compound in 68% yield:

MS(m/e): 444.3 (M⁺)

Calculated for C₂₂H₃₅FN₂O₆.0.25H₂O: Theory: C, 59.11; H, 8.01; N, 6.27.Found: C, 59.05; H, 7.85; N, 6.37

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5R)-5-fluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 329.3 (M⁺)

HRMS (m/z): [M+H]⁺ calcd for C₁₆H₂₅FN₂O, 329.1877; found 329.1903

¹³C NMR (D₂O):

174.7, 87.0 (d, J_(C-F)=173.2 Hz), 81.2 (d, J_(C-F)=170.6 Hz), 72.5 (d,J_(C-F)=228.2 Hz), 65.9, 54.4, 52.9, 50.4, 42.2, 32.2, 31.8, 30.1, 26.1,25.9, 20.2 ppm

EXAMPLE 26 Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-5-oxopiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3S)-(Ethoxycarbonyl)-5-oxopiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of DMSO (0.20 mL, 2.8 mmol) was cooled to −78° C. in CH₂Cl₂(10 mL) and charged with (COCl)₂ (0.13 mL, 1.4 mmol). The mixture wasstirred for 5 min, then 3S, 4aR, 6S, 8aR ethyl6-((3S)-(ethoxycarbonyl)-(5R)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.50 g, 1.1 mmol), the compound described in Step A of Example 20above, dissolved in CH₂Cl₂ (10 mL) was added. After 1 h, triethylamine(0.80 mL, 5.6 mmol) was added and the reaction was warmed to roomtemperature overnight. The mixture was partitioned between CH₂Cl₂ andsaturated aqueous NaHCO₃, extracted with CH₂Cl₂, washed with saturatedaqueous NaCl, dried (MgSO₄), and concentrated. Chromatography (stepwisegradient: CH₂Cl₂-10% EtOH/CH₂Cl₂) provided the title compound (0.47 g,98%):

MS(m/e): 439.3 (M⁺)

Calculated for C₂₇H₃₄N₂O₇.0.25H₂O: Theory: C, 59.65; H, 7.85; N, 6.32.Found: C, 59.32; H, 7.55; N, 6.32

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-5-oxopiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 325.4 (M⁺)

Calculated for C₁₆H₂₄N₂O₅.0.5H₂O: Theory: C, 57.65; H, 7.56; N, 8.40.Found: C, 57.79; H, 7.42; N, 8.56

EXAMPLE 27 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-5-oxopiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3R)-(Ethoxycarbonyl)-5-oxopiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of DMSO (0.75 mL, 10.5 mmol) was cooled to −78° C. in CH₂Cl₂(20 mL) and charged with (COCl)₂ (0.43 mL, 5.0 mmol). The mixture wasstirred for 5 min, then 3S, 4aR, 6S, 8aR ethyl6-((3R)-(ethoxycarbonyl)-(5R)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(1.85 g, 4.2 mmol), the compound described in Step B of Example 19above, dissolved in CH₂Cl₂ (25 mL) was added. After 0.75 h,triethylamine (2.94 mL, 20.9 mmol) was added and the reaction was warmedto room temperature overnight. The mixture was partitioned betweenCH₂Cl₂ and saturated aqueous NaHCO₃, extracted with CH₂Cl₂, washed withsaturated aqueous NaCl, dried (MgSO₄), and concentrated. Chromatography(stepwise gradient: CH₂Cl₂-10% EtOH/CH₂Cl₂) provided the title compound(1.03 g, 60%):

MS(m/e): 439.3 (M⁺)

Calculated for C₂₂H₃₄N₂O₇.0.25H₂O: Theory: C, 59.65; H, 7.85; N, 6.32.Found: C, 59.45; H, 7.57; N, 6.43

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-5-oxopiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 323.4 (M⁻)

Calculated for C₁₆H₂₄N₂O₅: Theory: C, 59.24; H, 7.46; N, 8.64. Found: C,58.87; H, 7.37; N, 8.85

EXAMPLE 28 Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-5,5-difluoropiperidinyl)-1, 2, 3, 4, 4a, 5, 6, 7, 8,8a-decahydroisoquinoline-3-carboxylic Acid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3S)-(Ethoxycarbonyl)-5,5-difluoropiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

To a solution of 3S, 4aR, 6S, 8aR ethyl6-((3S)-(ethoxycarbonyl)-5-oxopiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(520 mg, 1.2 mmol), the compound described in Step A of Example 26cooled to −78° C. in CH₂Cl₂ (15 mL) was added diethylaminosulfurtrifluoride (400 □L, 2.8 mmol). The reaction was warmed to roomtemperature, stirred for 48 h, quenched with EtOH, then concentrated invacuo. The residue was partitioned between CH₂Cl₂ and saturated aqueousNaHCO₃, extracted with CH₂Cl₂, washed with saturated aqueous NaCl, dried(MgSO₄), and concentrated. Chromatography (Stepwise gradient: hexane-50%EtOAc/hexane) provided the title compound (281 mg, 51%):

MS(m/e): 461.2 (M⁺)

Calculated for C₂₂H₃₄F₂N₂O₆.0.25H₂O: Theory: C, 56.83; H, 7.48; N, 6.02.Found: C, 56.78; H, 7.09; N, 6.25

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-5,5-difluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 347.2 (M⁺)

Calculated for C₁₆H₂₄F₂N₂O₅.0.75H₂O: Theory: C, 53.40; H, 7.14; N, 7.78.Found: C, 53.19; H, 7.01; N, 7.47

¹³C NMR (D₂O):

0177.0, 174.7, 119.4 (d, J_(C-F)=243.9 Hz), 66.6, 54.4, 52.1 (d,J_(C-F)=30.6 Hz), 50.1, 42.1, 38.6, 34.0 (d, J_(C-F)=23.5 Hz), 32.3,31.9, 30.0, 26.1, 24.8, 21.5 ppm

EXAMPLE 29 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-5,5-difluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3R)-(Ethoxycarbonyl)-5,5-difluoropiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

The title compound was prepared from the compound described in Step A ofExample 27 in the manner described for the preparation of the compounddescribed in Step A of Example 28.

MS(m/e): 461.4 (M⁺)

Calculated for C₂₂H₃₄F₂N₂O₆.0.25H₂O: Theory: C, 56.83; H, 7.48; N, 6.02.Found: C, 56.79; H, 7.16; N, 6.08.

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-5,5-difluoropiperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 347.2 (M⁺)

Calculated for C₁₆H₂₄F₂N₂O₄.1.0H₂O: Theory: C, 52.74; H, 7.19; N, 7.69.Found: C, 52.97; H, 7.02; N, 7.42

¹³C NMR (D₂O):

0177.0, 174.6, 119.4 (d, J_(C-F)=243.2H), 66.5, 54.4, 51.8 (d,J_(C-F)=33.9 Hz), 50.3, 42.1, 38.6, 34.0 (d, J_(C-F)=23.2 Hz), 32.3,31.8, 30.0, 26.0, 25.6, 21.0 ppm

EXAMPLE 30 Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5S)-5-(5-phenyltetrazol-2-yl)piperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-((3S)-(Ethoxycarbonyl)-(5S)-5-(5-phenyltetrazol-2-yl)piperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A solution of 3S, 4aR, 6S, 8aR ethyl6-((3S)-(ethoxycarbonyl)-(5R)-5-hydroxypiperidinyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate(0.59 g, 1.3 mmol), the compound described in Step A of Example 20 wascooled to 0° C. in THF (15 mL). Triphenylphosphine (1.4 g, 5.3 mmol),5-phenyltetrazole (0.78 g, 5.3 mmol), and diethyl azodicarboxylate (0.68g, 4.68 mmol) were added. After stirring at room temperature for 72 h,the reaction mixture was loaded onto a 5 g SCX Mega Bond Elut SPEcartridge (Varian Sample Preparation Products) and eluted with EtOH,followed by CH₂Cl₂. The product was removed with 2 M NH3/EtOH, and thesolution was concentrated then chromatographed (Stepwise gradient:hexane-50% EtOAc/hexane), to provide the title compound (0.39 g, 53%):

MS(m/e): 569.3 (M⁺)

Calculated for C₂₉)H₄N₆O₆: Theory: C, 61.25; H, 7.09; N, 14.78. Found:C, 61.41; H, 7.07; N, 14.52

B. Preparation of 3S, 4aR, 6S, 8aR 6-((3S)-3-(Carboxylicacid)-(5S)-5-(5-phenyltetrazol-2-yl)piperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

Acid hydrolysis of the compound from Step A above, using the proceduredescribed for the preparation of the compound in Step B of Example 21,provided the title compound as a white solid:

MS(m/e): 453.3 (M⁺)

HRMS (m/z): [M+H]⁺ calcd for C₂₃H₃₁N₆O₄, 455.2407; found 455.2433

EXAMPLE 31 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5R)-5-(5-phenyl-tetrazol-2-yl)piperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

The title compound was prepared in the same two Step sequence describedfor the preparation of the compound in Step B of Example 30, startingwith the compound described in Step B of Example 19:

MS(m/e): 453.2 (M⁺)

HRMS (m/z): [M+H]⁺ calcd for C₂₃H₃₁N₆O₄, 455.2407; found 455.2437

EXAMPLE 32 Preparation of 3S, 4aR, 6S, 8aR 6-((3R)-3-(Carboxylicacid)-(5R)-5-(5-phenyl-tetrazol-2-yl)piperidinyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

The title compound was prepared in the same two Step sequence describedfor the preparation of the compound in Step B of Example 30, startingwith the compound described in Step B of Example 19, and using5-propyltetrazole:

MS(m/e): 421.4 (M⁺)

HRMS (m/z): [M+H]⁺ calcd for C₂₀H₃₃N₆O₄, 421.2563; found 421.2588

EXAMPLE 33 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-pyrrolidinylmethyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(tert-Butoxycarbonyl)-pyrrolidinylmethyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of L-proline tert-butyl ester (0.44 g, 2.54 mmol), 3S, 4aR,6S, 8aRethyl-6-formyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) (0.75 g, 2.52 mmol), NaBH(OAc)₃(0.75 g, 3.53 mmol), and HOAc (0.15 mL, 2.53 mmol) was stirred at roomtemperature in THF (15 mL) for 18 h. The reaction mixture waspartitioned between 3:1 CHCl₃/IPA and saturated aqueous NaHCO₃,extracted with CHCl₃/IPA, washed with saturated aqueous NaCl, dried(MgSO₄), and concentrated. Chromatography (75% EtOAc/hexane) providedthe title compound (0.73 g, 64%):

MS(m/e): 453.3 (M⁺)

Calculated for C₂₄H₄₀N₂O₆: Theory: C, 63.69; H, 8.91; N, 6.19. Found: C,63.41; H, 8.83; N, 6.31

B. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-pyrrolidinylmethyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound from Step A above (1.35 g, 2.98 mmol)dissolved in 5 N aqueous HCl (20 mL) was heated at 100° C. for 48 h. Thereaction mixture was cooled to room temperature and concentrated invacuo. The resulting crude foam was dissolved in H₂O (75 mL) and stirredin the presence of Dowex 50×8 (100-200) ion-exchange resin (10 g) for 2h. The resin was filtered, washed sequentially with 1:1 THF/H₂O and H₂O,then stirred in the presence of 10% pyridine/H₂O for 2 h. Afterfiltration, the resin was washed with H₂O, and the filtrate wasconcentrated in vacuo to provide the title compound (0.78 g, 84%) as awhite foam:

MS(m/e): 311.3 (M⁺)

Calculated for C₁₆H₂₆N₂O₄.1.5H₂O: Theory: C, 57.00; H, 8.66; N, 8.30.Found: C, 57.03; H, 8.48; N, 8.18.

¹³C NMR (D₂O): δ 177.5, 176.1, 70.5, 62.5, 56.1, 53.1, 43.3, 35.5, 33.9,33.2, 32.3, 32.0, 29.9, 25.1, 23.8 ppm.

EXAMPLE 34 Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)-4-hydroxypyrrolidinylmethyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A. Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinylmethyl)-2-methoxycarbonyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of 4-hydroxy-L-proline ethyl ester (0.40 g, 2.53 mmol), 3S,4aR, 6S, 8aRethyl-6-formyl-2-methoxycarbonyl-decahydroisoquinoline-3-carboxylate(prepared by one of ordinary skill in the art following the proceduresas disclosed in U.S. Pat. No. 5,670,516) (0.75 g, 2.52 mmol), NaBH(OAc)₃(0.75 g, 3.53 mmol), and HOAc (0.15 mL, 2.53 mmol) was stirred at roomtemperature in THF (15 mL) for 18 h. The reaction mixture waspartitioned between 3:1 CHCl₃/IPA and saturated aqueous NaHCO₃,extracted with CHCl₃/IPA, washed with saturated aqueous NaCl, dried(MgSO₄), and concentrated. Chromatography (75% EtOAc/hexane) providedthe title compound (0.68 g, 61%):

MS(m/e): 441.3 (M⁺)

Preparation of 3S, 4aR, 6S, 8aR Ethyl6-(((2S)-2-(Ethoxycarbonyl)-(4R)-4-hydroxypyrrolidinylmethyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylate

A mixture of the compound prepared in Step A above (0.63 g, 1.43 mmol)and iodotrimethylsilane (1.0 mL, 7.15 mmol), was stirred at 45° C. inCH₂Cl₂ (10 mL) for 3 h. The reaction mixture was quenched by theaddition of saturated aqueous NaHCO3 and extracted with CH₂Cl₂. Thecombined organics were washed with saturated aqueous NaCl, dried(MgSO₄), and concentrated to provide the title compound (0.42 g, 77%).

C. Preparation of 3S, 4aR, 6S, 8aR 6-(((2S)-2-(Carboxylicacid)-(4R)₄-hydroxypyrrolidinylmethyl-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylicAcid

A solution of the compound from Step B above (0.42 g, 1.10 mmol)dissolved in 1:1 1 N aqueous NaOH/EtOH (5 mL) was heated at 50° C. for 4h. The reaction mixture was cooled to room temperature, the pH of thereaction was adjusted to −4 with 1 N aqueous HCl, and the reaction wasconcentrated in vacuo. The resulting crude foam was dissolved in H₂O (75mL) and stirred in the presence of Dowex 50×8 (100-200) ion-exchangeresin (10 g) for 2 h. The resin was filtered, washed sequentially with1:1 THF/H₂O and H₂O, then stirred in the presence of 10% pyridine/H₂Ofor 2 h. After filtration, the resin was washed with H₂O, and thefiltrate was concentrated in vacuo to provide the title compound (0.29g, 81%) as a white foam:

MS(m/e): 311.3 (M⁺)

Calculated for C₁₆H₂₆N₂O₅.2.0H₂O: Theory: C, 53.03; H, 8.34; N, 7.73.Found: C, 52.88; H, 8.21; N, 7.56

¹³C NMR (D₂O): δ 181.3, 178.7, 70.4, 69.7, 63.4, 62.2, 55.8, 43.6, 39.5,37.1, 34.9, 33.7, 32.9, 30.4, 28.9, 26.4 ppm

EXAMPLE 35

To establish that the iGluR₅ receptor subtype is mediating apharmacological response in a neurological disease or disorder, thebinding affinity of the panel compounds to the iGluR₅ receptor is firstmeasured using standard methods. For example, the activity of compoundsacting at the iGluR₅ receptor can be determined by radiolabelled ligandbinding studies at the cloned and expressed human iGluR₅ receptor(Korczak et al., 1994, Recept. Channels 3; 41-49), and by whole cellvoltage clamp electrophysiological recordings of currents in acutelyisolated rat dorsal root ganglion neurons (Bleakman et al., 1996, Mol.Pharmacol. 49; 581-585). The selectivity of compounds acting at theiGluR₅ receptor subtype can then be determined by comparing antagonistactivity at the iGluR₅ receptor with antagonist activity at other AMPAand kainate receptors. Methods useful for such comparison studiesinclude: receptor-ligand binding studies and whole-cell voltage clampelectrophysiological recordings of functional activity at human GluR₁,GluR₂, GluR₃ and GluR₄ receptors (Fletcher et al., 1995, Recept.Channels 3; 21-31); receptor-ligand binding studies and whole-cellvoltage clamp electrophysiological recordings of functional activity athuman GluR₆ receptors (Hoo et al., Recept. Channels 2;327-338); andwhole-cell voltage clamp electrophysiological recordings of functionalactivity at AMPA receptors in acutely isolated cerebellar Purkinjeneurons (Bleakman et al., 1996, Mol. Pharmacol. 49; 581-585) and othertissues expressing AMPA receptors (Fletcher and Lodge, 1996, Pharmacol.Ther. 70; 65-89).

iGluR₅ Antagonist Binding Affinity Profiles

Cell lines (HEK293 cells) stably transfected with human iGluR receptorsare employed. Displacement of ³[H] AMPA by increasing concentrations ofantagonist is measured on iGluR_(]), iGluR₂, iGluR₃, and iGluR₄expressing cells, while displacement of ³[H] kainate (K_(i)) is measuredon iGluR₅, iGluR₆, iGluR₇, and KA2-expressing cells. Estimatedantagonist binding activity (K_(i)) in μM, for example, is determinedfor Compounds of Formula I. As an indicia of selectivity, the ratio ofbinding affinity to the iGluR₂ AMPA receptor subtype, versus the bindingaffinity to iGluR₅ kainate receptor subtype (Ki at iGluR₂/K_(i) atiGluR5) is also determined. The iGluR5 receptor antagonist compounds, asprovided by the present invention, provide a K_(i) at the iGluR5receptor subtype of less than 5000 μM, preferably less than 500 μM, evenmore preferably less than 50 μM, and most preferably less than 5 μM. Thepreferred selective iGluR₅ receptor antagonists compounds, as providedby the present invention, display a greater binding affinity (lowerK_(i)) for iGluR₅ than that for iGluR₂, preferably at least 10 foldgreater for iGluR₅ than that for iGluR₂, and even more preferably atleast 100 fold, and most preferably at least 1000 fold. than that foriGluR₂.

EXAMPLE 36

The following animal model may be employed to determine the ability ofeach of the compounds of Formula I to inhibit protein extravasation, anexemplary functional assay of the neuronal mechanism of migraine.

Animal Model of Dural Protein Extravasation

Harlan Sprague-Dawley rats (225-325 g) or guinea pigs from Charles RiverLaboratories (225-325 g) are anesthetized with sodium pentobarbitalintraperitoneally (65 mg/kg or 45 mg/kg respectively) and placed in astereotaxic frame (David Kopf Instruments) with the incisor bar set at−3.5 mm for rats or 4.0 mm for guinea pigs. Following a midline sagitalscalp incision, two pairs of bilateral holes are drilled through theskull (6 mm posterially, 2.0 and 4.0 mm laterally in rats; 4 mmposteriorly and 3.2 and 5.2 mm laterally in guinea pigs, all coordinatesreferenced to bregma). Pairs of stainless steel stimulating electrodes,insulated except at the tips (Rhodes Medical Systems, Inc.), are loweredthrough the holes in both hemispheres to a depth of 9 mm (rats) or 10.5mm (guinea pigs) from dura.

The femoral vein is exposed and a dose of the test compound is injectedintravenously (i.v.) at a dosing volume of 1 ml/kg or, in thealternative, test compound is administered orally (p.o) via gavage at avolume of 2.0 ml/kg. Approximately 7 minutes post i.v. injection, a 50mg/kg dose of Evans Blue, a fluorescent dye, is also injectedintravenously. The Evans Blue complexes with proteins in the blood andfunctions as a marker for protein extravasation. Exactly 10 minutespost-injection of the test compound, the left trigeminal ganglion isstimulated for 3 minutes at a current intensity of 1.0 mA (5 Hz, 4 msecduration) with a Model 273 potentiostat/galvanostat (EG&G PrincetonApplied Research).

Fifteen minutes following stimulation, the animals are euthanized byexsanguination with 20 mL of saline. The top of the skull is removed tofacilitate the collection of the dural membranes. The membrane samplesare removed from both hemispheres, rinsed with water, and spread flat onmicroscopic slides. Once dried, the tissues are coverslipped with a 70%glycerol/water solution.

A fluorescence microscope (Zeiss) equipped with a grating monchromatorand a spectrophotometer is used to quantify the amount of Evans Blue dyein each sample. An excitation wavelength of approximately 535 nm isutilized and the emission intensity at 600 nm is determined. Themicroscope is equipped with a motorized stage and also interfaced with apersonal computer. This facilitates the computer-controlled movement ofthe stage with fluorescence measurements at 25 points (500 mm steps) oneach dural sample. The mean and standard deviation of the measurementsare determined by the computer.

The extravasation induced by the electrical stimulation of thetrigeminal ganglion has an ipsilateral effect (i.e. occurs only on theside of the dura in which the trigeminal ganglion was stimulated). Thisallows the other (unstimulated) half of the dura to be used as acontrol. The ratio (“extravasation ratio”) of the amount ofextravasation in the dura from the stimulated side, over the amount ofextravasation in the unstimulated side, is calculated. Control animalsdosed with only with saline, yield an extravasation ratio ofapproximately 2.0 in rats and apprximately 1.8 in guinea pigs. Incontrast, a compound that completely prevents the extravasation in thedura from the stimulated side would yield a ratio of approximately 1.0.

Dose-response curves are generated for each of the compounds of FormulaI and the dose that inhibits the extravasation by 50% (ID₅₀) or 100%(ID₁₀₀) is approximated.

EXAMPLE 37

To demonstrate the utility of compounds of the present invention totreat pain or provide analgesic effects, several well known animalmodels may be employed. For example, international application WO98/45270 describes the well known Formalin Test, which is describedbelow:

Formalin Test

For example, male Sprague-Dawley rats (200-250 g; Charles River,Portage, Mich.) are housed in group cages and maintained in a constanttemperature and a 12 hour light/12 hour dark cycle 4-7 days beforestudies are performed. Animals have free access to food and water at alltimes prior to the day of the experiment.

Drugs or vehicles are administered intraperitoneally (i.p.) or orally(p.o.) by gavage in a volume of about 1 ml/kg. The test is performed incustom made Plexiglas® boxes about 25×25×20 cm in size (according toShibata et al., Pain 38;347-352, 1989, Wheeler-Aceto et al., Pain, 40;229-238,1990). A mirror placed at the back of the cage allows theunhindered observation of the formalin injected paw. Rats are acclimatedindividually in the cubicles at least 1 hour prior to the experiment.All testing is conducted between, for example, 08:00 and 14:00 h and thetesting room temperature is maintained at about 21-23° C.

Test compounds are administered about 30 minutes prior to the formalininjection. Formalin (50 micoliters of a 5% solution in saline) isinjected subcutaneously into the dorsal lateral surface of the righthind paw with a 27 gauge needle. Observation is started immediatelyafter the formalin injection. Formalin-induced pain is quantified byrecording, for example, in 5 minute intervals, the number of formalininjected pawlicking events and the number of seconds each licking eventlasts. These recordings are made for about 50 minutes after the formalininjection.

Several different scoring parameters have been reported for the formalintest. The total time spent licking and biting the injected paw isdemonstrated to be most relevant (Coderre et al., Eur. J. Neurosci. 6;1328-1334, 1993; Abbott et al., Pain, 60; 91-102, 1995) and may bechosen for the testing score. The early phase score is the sum of timespent licking, in seconds, from time 0 to 5 minutes. The late phase isscored in 5 minute blocks from 15 minutes to 40 minutes and is expressedaccordingly or also by adding the total number of seconds spent lickingfrom minute 15 to minute 40 of the observation period.

Data may be presented as means with standard errors of means (±SEM).Data may also be evaluated by one-way analysis of variance (ANOVA) andthe appropriate contrasts analyzed by Dunnett “t” test for two sidedcomparisons. Differences are considered to be significant if, forexample, the P-value is less than 0.05. Statistics may be determined atthe 5 minute time point and at 5 minute intervals between 15 and 40minutes. Where data are expressed as total amount of time spent lickingin the late phase, statistics may be performed on the total time spentlicking as well and may be indicated accordingly.

In addition to the Formalin Test, the well known Mouse Writhing Test,essentially as described in published International Application WO00/028,980, may also be employed to demonstrate the analgesic propertiesof compounds of the present invention.

Mouse Writhing Test

An accepted procedure for detecting and comparing the analgesic activityof different classes of analgesic drugs, for which there is a goodcorrelation with human analgesic activity, is the prevention of aceticacid-induced writhing in mice. Mice are orally administered variousdoses of a test compound or placebo prior to testing. The mice are theninjected intraperitoneally with acetic acid (0.55% solution, 10 mL/kg)five minutes prior to a designated observation period. Inhibition ofwrithing behavior is demonstrative of analgesic activity. Haubrich etal., “Pharmacology of pravadoline: a new analgesic agent”, The Journalof Pharmacology and Experimental Therapeutics, 255 (1990) 511-522. Forscoring purposes “writhe” is indicated by whole body stretching orcontracting of the abdomen during an observation period beginning aboutfive minutes after receiving the acetic acid.

ED₅₀ values, and their standard error of means (SEM), are determinedusing accepted numerical methods for all test compounds administered.For example, see R. E. Kirk (1982) “Experimental Design: Procedures forthe behavioral sciences,” 2nd ed. One method to establish thesignificance of the analgesic activity of a given test compound comparedto that of another is to calculate the SEM values for each ED₅₀ value.If the SEM values do not overlap the line of addition, then the ED50values are significantly different from the line of addition.

Yet another accepted animal model to demonstrate the ability of aparticular compound to treat pain, or provide analgesic effects, is thewell known Rat Model of Carrageenan-induced Thermal Hyperalgesia, alsodescribed in published International Application WO 00/028,980.

Carrageenan-Induced Thermal Hyperalgesia in Rats

Another accepted method for detecting and comparing the analgesicactivity of different classes of analgesic compounds for which there isgood correlation with human analgesic activity is the reversal ofcarrageenan-induced thermal hyperalgesia in rats (Hargreaves et al. Pain32:77-88, 1988).

Rats are administered a dose test compound or vehicle and then injectedsubcutaneously into one hindpaw, with carrageenan (1.5% w/v, 100 μl).The response to noxious thermal stimulus is determined two hours laterusing a commercially available thermal plantar device (Ugo Basil, Italy)according to established methods (Hargreaves et al. Pain 32:77-88,1988). Briefly, animals are habituated to a plastic behavioral enclosurefor 5 min. A heat source is positioned directly beneath a hindpaw andthe time taken for hindpaw withdrawal monitored automatically. If theanimal does not respond within 20 sec, the stimulus is automaticallyterminated to prevent tissue damage. Measurements for both the injuredand contralateral (control) hindpaw are recorded. Thermal hyperalgesiais evidenced by a shorter response latency by the injured as compared tothe control paw.

ED₅₀ values and their standard error of means (SEM) are determined usingaccepted numerical methods. For example, see R. E. Kirk (1982)“Experimental Design: Procedures for the behavioral sciences,” 2nd ed.

1. A compound of the formula:

wherein, R¹ represents hydrogen, chlorine, bromine, iodine, fluorine,SR³, or hydroxy; R² represents hydrogen or fluorine, with the provisothat where R¹ is other than fluorine, then R² represents hydrogen; andR³ represents tetrazole, substituted tetrazole, triazole, (C₁-C₄)alkyl,or (C₁-C₄)alkyl-CO₂H; with the further proviso that where R¹ and R² eachindependently represent fluorine, the compound is of the formula

or a pharmaceutically acceptable salt or prodrug thereof.
 2. A compoundof formula:

wherein, R² represents hydrogen or fluorine; R⁴ represents hydrogen,chlorine, bromine, iodine, fluorine, SR⁷, or hydroxy, with the provisothat where R⁴ is other than fluorine, then R² represents hydrogen; R⁷represents tetrazole, substituted tetrazole, triazole, (C₁-C₄)alkyl,(C₁-C₄)alkyl-CO₂R⁸; and R⁵, R⁶, and R⁸ each independently representhydrogen, (C₁-C₂₀)alkyl, (C₂-C₆)alkenyl, (C₁-C₆)alkylaryl,(C₁-C₆)alkyl(C₃-C₁₀)cycloalkyl, (C₁-C₆)alkyl-N,N—C₁-C₆ dialkylamine,(C₁-C₆)alkyl-pyrrolidine, (C₁-C₆)alkyl-piperidine, or(C₁-C₆)alkyl-morpholine, with the proviso that at least one of R⁵, R⁶,or R⁸ is other than hydrogen; with the further proviso that where R² andR⁴ each independently represent fluorine, then the compound is of theformula

or a pharmaceutically acceptable salt thereof.
 3. The compound accordingto claim 2 wherein R⁵ represents hydrogen and R⁶ represents(C₁-C₂₀)alkyl.
 4. The compound according to claim 3 wherein R⁶represents (C₁-C₆)alkyl.
 5. The compound according to claim 2 wherein R⁵represents (C₁-C₂₀)alkyl and R6 represents hydrogen.
 6. The compoundaccording to claim 5 wherein R⁵ represents (C₁-C₆)alkyl.
 7. The compoundaccording to claim 2 wherein R⁵ and R⁶ each independently represent(C₁-C₂₀)alkyl.
 8. The compound according to claim 7 wherein R⁵ and R⁶each independently represent (C₁-C₆)alkyl.
 9. The compound according toclaim 8 wherein R⁵ and R⁶ each independently represent ethyl.
 10. Acompound of the formula

wherein, R⁹ represents hydrogen, chlorine, bromine, iodine, fluorine,hydroxy, tetrazole, or a group of the formula:

wherein X represents (C₁-C₄)alkyl or phenyl; and R¹⁰ represents hydrogenor fluorine, with the proviso that where R⁹ is other than fluorine, thenR¹⁰ represents hydrogen, or a pharmaceutically acceptable salt orprodrug thereof.
 11. A compound of the formula

wherein, R⁹ represents hydrogen, chlorine, bromine, iodine, fluorine,hydroxy, tetrazole, or a group of the formula:

wherein X represents (C₁-C₄)alkyl or phenyl; R¹⁰ represents hydrogen orfluorine, with the proviso that where R⁹ is other than fluorine, thenR¹⁰ represents hydrogen, R¹¹ and R¹² each independently representhydrogen, (C₁-C₂₀)alkyl, (C₂-C₆)alkenyl, (C₁-C₆)alkylaryl,(C₁-C₆)alkyl(C₃-C₁₀)cycloalkyl, (C₁-C₆)alkyl-N,N—C₁-C₆ dialkylamine,(C₁-C₆)alkyl-pyrrolidine, (C₁-C₆)alkyl-piperidine, or(C₁-C₆)alkyl-morpholine, with the proviso that at least one of R¹¹ orR¹² is other than hydrogen, or a pharmaceutically acceptable saltthereof.
 12. The compound according to claim 11 wherein R¹¹ representshydrogen and R¹² represents (C₁-C₂₀)alkyl.
 13. The compound according toclaim 12 wherein R¹² represents (C₁-C₆)alkyl.
 14. The compound accordingto claim 11 wherein R¹¹ represents (C₁-C₂₀)alkyl and R¹² representshydrogen.
 15. The compound according to claim 14 wherein R¹¹ represents(C₁-C₆)alkyl.
 16. The compound according to claim 11 wherein R¹¹ and R¹²each independently represent (C₁-C₂₀)alkyl.
 17. The compound accordingto claim 16 wherein R¹¹ and R¹² each independently represent(C₁-C₆)alkyl.
 18. The compound according to claim 17 wherein R¹¹ and R¹²each independently represent ethyl.
 19. A method of treating aneurological disorder or neurodegenerative disease which comprisesadministering to a patient in need thereof an effective amount of acompound according to claim
 1. 20. The method according to claim 19wherein the neurological disorder is migraine.
 21. The method accordingto claim 19 wherein the neurological disorder is pain.
 22. Apharmaceutical composition comprising an effective amount of a compoundaccording to claim 1 in combination with a pharmaceutically acceptablecarrier, diluent, or excipient.
 23. (canceled)
 24. (canceled) 25.(canceled)
 26. (canceled)
 27. (canceled)
 28. (canceled)
 29. A method oftreating a neurological disorder or neurodegenerative disease whichcomprises administering to a patient in need thereof an effective amountof a compound according to claim
 2. 30. A method of treating aneurological disorder or neurodegenerative disease which comprisesadministering to a patient in need thereof an effective amount of acompound according to claim
 10. 31. A method of treating a neurologicaldisorder or neurodegenerative disease which comprises administering to apatient in need thereof an effective amount of a compound according toclaim
 11. 32. A pharmaceutical composition comprising an effectiveamount of a compound according to claim 2 in combination with apharmaceutically acceptable carrier, diluent, or excipient.
 33. Apharmaceutical composition comprising an effective amount of a compoundaccording to claim 10 in combination with a pharmaceutically acceptablecarrier, diluent, or excipient.
 34. A pharmaceutical compositioncomprising an effective amount of a compound according to claim 11 incombination with a pharmaceutically acceptable carrier, diluent, orexcipient.